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| author | monster <monster@ydb.tech> | 2022-07-07 14:41:37 +0300 |
|---|---|---|
| committer | monster <monster@ydb.tech> | 2022-07-07 14:41:37 +0300 |
| commit | 06e5c21a835c0e923506c4ff27929f34e00761c2 (patch) | |
| tree | 75efcbc6854ef9bd476eb8bf00cc5c900da436a2 /contrib/tools/python3/src/Lib/pydoc_data/topics.py | |
| parent | 03f024c4412e3aa613bb543cf1660176320ba8f4 (diff) | |
| download | ydb-06e5c21a835c0e923506c4ff27929f34e00761c2.tar.gz | |
fix ya.make
Diffstat (limited to 'contrib/tools/python3/src/Lib/pydoc_data/topics.py')
| -rw-r--r-- | contrib/tools/python3/src/Lib/pydoc_data/topics.py | 15355 |
1 files changed, 0 insertions, 15355 deletions
diff --git a/contrib/tools/python3/src/Lib/pydoc_data/topics.py b/contrib/tools/python3/src/Lib/pydoc_data/topics.py deleted file mode 100644 index 17f0cb4f20..0000000000 --- a/contrib/tools/python3/src/Lib/pydoc_data/topics.py +++ /dev/null @@ -1,15355 +0,0 @@ -# -*- coding: utf-8 -*- -# Autogenerated by Sphinx on Mon Jun 6 12:53:10 2022 -topics = {'assert': 'The "assert" statement\n' - '**********************\n' - '\n' - 'Assert statements are a convenient way to insert debugging ' - 'assertions\n' - 'into a program:\n' - '\n' - ' assert_stmt ::= "assert" expression ["," expression]\n' - '\n' - 'The simple form, "assert expression", is equivalent to\n' - '\n' - ' if __debug__:\n' - ' if not expression: raise AssertionError\n' - '\n' - 'The extended form, "assert expression1, expression2", is ' - 'equivalent to\n' - '\n' - ' if __debug__:\n' - ' if not expression1: raise AssertionError(expression2)\n' - '\n' - 'These equivalences assume that "__debug__" and "AssertionError" ' - 'refer\n' - 'to the built-in variables with those names. In the current\n' - 'implementation, the built-in variable "__debug__" is "True" under\n' - 'normal circumstances, "False" when optimization is requested ' - '(command\n' - 'line option "-O"). The current code generator emits no code for ' - 'an\n' - 'assert statement when optimization is requested at compile time. ' - 'Note\n' - 'that it is unnecessary to include the source code for the ' - 'expression\n' - 'that failed in the error message; it will be displayed as part of ' - 'the\n' - 'stack trace.\n' - '\n' - 'Assignments to "__debug__" are illegal. The value for the ' - 'built-in\n' - 'variable is determined when the interpreter starts.\n', - 'assignment': 'Assignment statements\n' - '*********************\n' - '\n' - 'Assignment statements are used to (re)bind names to values and ' - 'to\n' - 'modify attributes or items of mutable objects:\n' - '\n' - ' assignment_stmt ::= (target_list "=")+ (starred_expression ' - '| yield_expression)\n' - ' target_list ::= target ("," target)* [","]\n' - ' target ::= identifier\n' - ' | "(" [target_list] ")"\n' - ' | "[" [target_list] "]"\n' - ' | attributeref\n' - ' | subscription\n' - ' | slicing\n' - ' | "*" target\n' - '\n' - '(See section Primaries for the syntax definitions for ' - '*attributeref*,\n' - '*subscription*, and *slicing*.)\n' - '\n' - 'An assignment statement evaluates the expression list ' - '(remember that\n' - 'this can be a single expression or a comma-separated list, the ' - 'latter\n' - 'yielding a tuple) and assigns the single resulting object to ' - 'each of\n' - 'the target lists, from left to right.\n' - '\n' - 'Assignment is defined recursively depending on the form of the ' - 'target\n' - '(list). When a target is part of a mutable object (an ' - 'attribute\n' - 'reference, subscription or slicing), the mutable object must\n' - 'ultimately perform the assignment and decide about its ' - 'validity, and\n' - 'may raise an exception if the assignment is unacceptable. The ' - 'rules\n' - 'observed by various types and the exceptions raised are given ' - 'with the\n' - 'definition of the object types (see section The standard type\n' - 'hierarchy).\n' - '\n' - 'Assignment of an object to a target list, optionally enclosed ' - 'in\n' - 'parentheses or square brackets, is recursively defined as ' - 'follows.\n' - '\n' - '* If the target list is a single target with no trailing ' - 'comma,\n' - ' optionally in parentheses, the object is assigned to that ' - 'target.\n' - '\n' - '* Else:\n' - '\n' - ' * If the target list contains one target prefixed with an ' - 'asterisk,\n' - ' called a “starred” target: The object must be an iterable ' - 'with at\n' - ' least as many items as there are targets in the target ' - 'list, minus\n' - ' one. The first items of the iterable are assigned, from ' - 'left to\n' - ' right, to the targets before the starred target. The ' - 'final items\n' - ' of the iterable are assigned to the targets after the ' - 'starred\n' - ' target. A list of the remaining items in the iterable is ' - 'then\n' - ' assigned to the starred target (the list can be empty).\n' - '\n' - ' * Else: The object must be an iterable with the same number ' - 'of items\n' - ' as there are targets in the target list, and the items ' - 'are\n' - ' assigned, from left to right, to the corresponding ' - 'targets.\n' - '\n' - 'Assignment of an object to a single target is recursively ' - 'defined as\n' - 'follows.\n' - '\n' - '* If the target is an identifier (name):\n' - '\n' - ' * If the name does not occur in a "global" or "nonlocal" ' - 'statement\n' - ' in the current code block: the name is bound to the object ' - 'in the\n' - ' current local namespace.\n' - '\n' - ' * Otherwise: the name is bound to the object in the global ' - 'namespace\n' - ' or the outer namespace determined by "nonlocal", ' - 'respectively.\n' - '\n' - ' The name is rebound if it was already bound. This may cause ' - 'the\n' - ' reference count for the object previously bound to the name ' - 'to reach\n' - ' zero, causing the object to be deallocated and its ' - 'destructor (if it\n' - ' has one) to be called.\n' - '\n' - '* If the target is an attribute reference: The primary ' - 'expression in\n' - ' the reference is evaluated. It should yield an object with\n' - ' assignable attributes; if this is not the case, "TypeError" ' - 'is\n' - ' raised. That object is then asked to assign the assigned ' - 'object to\n' - ' the given attribute; if it cannot perform the assignment, it ' - 'raises\n' - ' an exception (usually but not necessarily ' - '"AttributeError").\n' - '\n' - ' Note: If the object is a class instance and the attribute ' - 'reference\n' - ' occurs on both sides of the assignment operator, the ' - 'right-hand side\n' - ' expression, "a.x" can access either an instance attribute or ' - '(if no\n' - ' instance attribute exists) a class attribute. The left-hand ' - 'side\n' - ' target "a.x" is always set as an instance attribute, ' - 'creating it if\n' - ' necessary. Thus, the two occurrences of "a.x" do not ' - 'necessarily\n' - ' refer to the same attribute: if the right-hand side ' - 'expression\n' - ' refers to a class attribute, the left-hand side creates a ' - 'new\n' - ' instance attribute as the target of the assignment:\n' - '\n' - ' class Cls:\n' - ' x = 3 # class variable\n' - ' inst = Cls()\n' - ' inst.x = inst.x + 1 # writes inst.x as 4 leaving Cls.x ' - 'as 3\n' - '\n' - ' This description does not necessarily apply to descriptor\n' - ' attributes, such as properties created with "property()".\n' - '\n' - '* If the target is a subscription: The primary expression in ' - 'the\n' - ' reference is evaluated. It should yield either a mutable ' - 'sequence\n' - ' object (such as a list) or a mapping object (such as a ' - 'dictionary).\n' - ' Next, the subscript expression is evaluated.\n' - '\n' - ' If the primary is a mutable sequence object (such as a ' - 'list), the\n' - ' subscript must yield an integer. If it is negative, the ' - 'sequence’s\n' - ' length is added to it. The resulting value must be a ' - 'nonnegative\n' - ' integer less than the sequence’s length, and the sequence is ' - 'asked\n' - ' to assign the assigned object to its item with that index. ' - 'If the\n' - ' index is out of range, "IndexError" is raised (assignment to ' - 'a\n' - ' subscripted sequence cannot add new items to a list).\n' - '\n' - ' If the primary is a mapping object (such as a dictionary), ' - 'the\n' - ' subscript must have a type compatible with the mapping’s key ' - 'type,\n' - ' and the mapping is then asked to create a key/datum pair ' - 'which maps\n' - ' the subscript to the assigned object. This can either ' - 'replace an\n' - ' existing key/value pair with the same key value, or insert a ' - 'new\n' - ' key/value pair (if no key with the same value existed).\n' - '\n' - ' For user-defined objects, the "__setitem__()" method is ' - 'called with\n' - ' appropriate arguments.\n' - '\n' - '* If the target is a slicing: The primary expression in the ' - 'reference\n' - ' is evaluated. It should yield a mutable sequence object ' - '(such as a\n' - ' list). The assigned object should be a sequence object of ' - 'the same\n' - ' type. Next, the lower and upper bound expressions are ' - 'evaluated,\n' - ' insofar they are present; defaults are zero and the ' - 'sequence’s\n' - ' length. The bounds should evaluate to integers. If either ' - 'bound is\n' - ' negative, the sequence’s length is added to it. The ' - 'resulting\n' - ' bounds are clipped to lie between zero and the sequence’s ' - 'length,\n' - ' inclusive. Finally, the sequence object is asked to replace ' - 'the\n' - ' slice with the items of the assigned sequence. The length ' - 'of the\n' - ' slice may be different from the length of the assigned ' - 'sequence,\n' - ' thus changing the length of the target sequence, if the ' - 'target\n' - ' sequence allows it.\n' - '\n' - '**CPython implementation detail:** In the current ' - 'implementation, the\n' - 'syntax for targets is taken to be the same as for expressions, ' - 'and\n' - 'invalid syntax is rejected during the code generation phase, ' - 'causing\n' - 'less detailed error messages.\n' - '\n' - 'Although the definition of assignment implies that overlaps ' - 'between\n' - 'the left-hand side and the right-hand side are ‘simultaneous’ ' - '(for\n' - 'example "a, b = b, a" swaps two variables), overlaps *within* ' - 'the\n' - 'collection of assigned-to variables occur left-to-right, ' - 'sometimes\n' - 'resulting in confusion. For instance, the following program ' - 'prints\n' - '"[0, 2]":\n' - '\n' - ' x = [0, 1]\n' - ' i = 0\n' - ' i, x[i] = 1, 2 # i is updated, then x[i] is ' - 'updated\n' - ' print(x)\n' - '\n' - 'See also:\n' - '\n' - ' **PEP 3132** - Extended Iterable Unpacking\n' - ' The specification for the "*target" feature.\n' - '\n' - '\n' - 'Augmented assignment statements\n' - '===============================\n' - '\n' - 'Augmented assignment is the combination, in a single ' - 'statement, of a\n' - 'binary operation and an assignment statement:\n' - '\n' - ' augmented_assignment_stmt ::= augtarget augop ' - '(expression_list | yield_expression)\n' - ' augtarget ::= identifier | attributeref | ' - 'subscription | slicing\n' - ' augop ::= "+=" | "-=" | "*=" | "@=" | ' - '"/=" | "//=" | "%=" | "**="\n' - ' | ">>=" | "<<=" | "&=" | "^=" | "|="\n' - '\n' - '(See section Primaries for the syntax definitions of the last ' - 'three\n' - 'symbols.)\n' - '\n' - 'An augmented assignment evaluates the target (which, unlike ' - 'normal\n' - 'assignment statements, cannot be an unpacking) and the ' - 'expression\n' - 'list, performs the binary operation specific to the type of ' - 'assignment\n' - 'on the two operands, and assigns the result to the original ' - 'target.\n' - 'The target is only evaluated once.\n' - '\n' - 'An augmented assignment expression like "x += 1" can be ' - 'rewritten as\n' - '"x = x + 1" to achieve a similar, but not exactly equal ' - 'effect. In the\n' - 'augmented version, "x" is only evaluated once. Also, when ' - 'possible,\n' - 'the actual operation is performed *in-place*, meaning that ' - 'rather than\n' - 'creating a new object and assigning that to the target, the ' - 'old object\n' - 'is modified instead.\n' - '\n' - 'Unlike normal assignments, augmented assignments evaluate the ' - 'left-\n' - 'hand side *before* evaluating the right-hand side. For ' - 'example, "a[i]\n' - '+= f(x)" first looks-up "a[i]", then it evaluates "f(x)" and ' - 'performs\n' - 'the addition, and lastly, it writes the result back to ' - '"a[i]".\n' - '\n' - 'With the exception of assigning to tuples and multiple targets ' - 'in a\n' - 'single statement, the assignment done by augmented assignment\n' - 'statements is handled the same way as normal assignments. ' - 'Similarly,\n' - 'with the exception of the possible *in-place* behavior, the ' - 'binary\n' - 'operation performed by augmented assignment is the same as the ' - 'normal\n' - 'binary operations.\n' - '\n' - 'For targets which are attribute references, the same caveat ' - 'about\n' - 'class and instance attributes applies as for regular ' - 'assignments.\n' - '\n' - '\n' - 'Annotated assignment statements\n' - '===============================\n' - '\n' - '*Annotation* assignment is the combination, in a single ' - 'statement, of\n' - 'a variable or attribute annotation and an optional assignment\n' - 'statement:\n' - '\n' - ' annotated_assignment_stmt ::= augtarget ":" expression\n' - ' ["=" (starred_expression | ' - 'yield_expression)]\n' - '\n' - 'The difference from normal Assignment statements is that only ' - 'single\n' - 'target is allowed.\n' - '\n' - 'For simple names as assignment targets, if in class or module ' - 'scope,\n' - 'the annotations are evaluated and stored in a special class or ' - 'module\n' - 'attribute "__annotations__" that is a dictionary mapping from ' - 'variable\n' - 'names (mangled if private) to evaluated annotations. This ' - 'attribute is\n' - 'writable and is automatically created at the start of class or ' - 'module\n' - 'body execution, if annotations are found statically.\n' - '\n' - 'For expressions as assignment targets, the annotations are ' - 'evaluated\n' - 'if in class or module scope, but not stored.\n' - '\n' - 'If a name is annotated in a function scope, then this name is ' - 'local\n' - 'for that scope. Annotations are never evaluated and stored in ' - 'function\n' - 'scopes.\n' - '\n' - 'If the right hand side is present, an annotated assignment ' - 'performs\n' - 'the actual assignment before evaluating annotations (where\n' - 'applicable). If the right hand side is not present for an ' - 'expression\n' - 'target, then the interpreter evaluates the target except for ' - 'the last\n' - '"__setitem__()" or "__setattr__()" call.\n' - '\n' - 'See also:\n' - '\n' - ' **PEP 526** - Syntax for Variable Annotations\n' - ' The proposal that added syntax for annotating the types ' - 'of\n' - ' variables (including class variables and instance ' - 'variables),\n' - ' instead of expressing them through comments.\n' - '\n' - ' **PEP 484** - Type hints\n' - ' The proposal that added the "typing" module to provide a ' - 'standard\n' - ' syntax for type annotations that can be used in static ' - 'analysis\n' - ' tools and IDEs.\n' - '\n' - 'Changed in version 3.8: Now annotated assignments allow same\n' - 'expressions in the right hand side as the regular ' - 'assignments.\n' - 'Previously, some expressions (like un-parenthesized tuple ' - 'expressions)\n' - 'caused a syntax error.\n', - 'async': 'Coroutines\n' - '**********\n' - '\n' - 'New in version 3.5.\n' - '\n' - '\n' - 'Coroutine function definition\n' - '=============================\n' - '\n' - ' async_funcdef ::= [decorators] "async" "def" funcname "(" ' - '[parameter_list] ")"\n' - ' ["->" expression] ":" suite\n' - '\n' - 'Execution of Python coroutines can be suspended and resumed at ' - 'many\n' - 'points (see *coroutine*). "await" expressions, "async for" and ' - '"async\n' - 'with" can only be used in the body of a coroutine function.\n' - '\n' - 'Functions defined with "async def" syntax are always coroutine\n' - 'functions, even if they do not contain "await" or "async" ' - 'keywords.\n' - '\n' - 'It is a "SyntaxError" to use a "yield from" expression inside the ' - 'body\n' - 'of a coroutine function.\n' - '\n' - 'An example of a coroutine function:\n' - '\n' - ' async def func(param1, param2):\n' - ' do_stuff()\n' - ' await some_coroutine()\n' - '\n' - 'Changed in version 3.7: "await" and "async" are now keywords;\n' - 'previously they were only treated as such inside the body of a\n' - 'coroutine function.\n' - '\n' - '\n' - 'The "async for" statement\n' - '=========================\n' - '\n' - ' async_for_stmt ::= "async" for_stmt\n' - '\n' - 'An *asynchronous iterable* provides an "__aiter__" method that\n' - 'directly returns an *asynchronous iterator*, which can call\n' - 'asynchronous code in its "__anext__" method.\n' - '\n' - 'The "async for" statement allows convenient iteration over\n' - 'asynchronous iterables.\n' - '\n' - 'The following code:\n' - '\n' - ' async for TARGET in ITER:\n' - ' SUITE\n' - ' else:\n' - ' SUITE2\n' - '\n' - 'Is semantically equivalent to:\n' - '\n' - ' iter = (ITER)\n' - ' iter = type(iter).__aiter__(iter)\n' - ' running = True\n' - '\n' - ' while running:\n' - ' try:\n' - ' TARGET = await type(iter).__anext__(iter)\n' - ' except StopAsyncIteration:\n' - ' running = False\n' - ' else:\n' - ' SUITE\n' - ' else:\n' - ' SUITE2\n' - '\n' - 'See also "__aiter__()" and "__anext__()" for details.\n' - '\n' - 'It is a "SyntaxError" to use an "async for" statement outside the ' - 'body\n' - 'of a coroutine function.\n' - '\n' - '\n' - 'The "async with" statement\n' - '==========================\n' - '\n' - ' async_with_stmt ::= "async" with_stmt\n' - '\n' - 'An *asynchronous context manager* is a *context manager* that is ' - 'able\n' - 'to suspend execution in its *enter* and *exit* methods.\n' - '\n' - 'The following code:\n' - '\n' - ' async with EXPRESSION as TARGET:\n' - ' SUITE\n' - '\n' - 'is semantically equivalent to:\n' - '\n' - ' manager = (EXPRESSION)\n' - ' aenter = type(manager).__aenter__\n' - ' aexit = type(manager).__aexit__\n' - ' value = await aenter(manager)\n' - ' hit_except = False\n' - '\n' - ' try:\n' - ' TARGET = value\n' - ' SUITE\n' - ' except:\n' - ' hit_except = True\n' - ' if not await aexit(manager, *sys.exc_info()):\n' - ' raise\n' - ' finally:\n' - ' if not hit_except:\n' - ' await aexit(manager, None, None, None)\n' - '\n' - 'See also "__aenter__()" and "__aexit__()" for details.\n' - '\n' - 'It is a "SyntaxError" to use an "async with" statement outside the\n' - 'body of a coroutine function.\n' - '\n' - 'See also:\n' - '\n' - ' **PEP 492** - Coroutines with async and await syntax\n' - ' The proposal that made coroutines a proper standalone concept ' - 'in\n' - ' Python, and added supporting syntax.\n' - '\n' - '-[ Footnotes ]-\n' - '\n' - '[1] The exception is propagated to the invocation stack unless ' - 'there\n' - ' is a "finally" clause which happens to raise another ' - 'exception.\n' - ' That new exception causes the old one to be lost.\n' - '\n' - '[2] In pattern matching, a sequence is defined as one of the\n' - ' following:\n' - '\n' - ' * a class that inherits from "collections.abc.Sequence"\n' - '\n' - ' * a Python class that has been registered as\n' - ' "collections.abc.Sequence"\n' - '\n' - ' * a builtin class that has its (CPython) ' - '"Py_TPFLAGS_SEQUENCE"\n' - ' bit set\n' - '\n' - ' * a class that inherits from any of the above\n' - '\n' - ' The following standard library classes are sequences:\n' - '\n' - ' * "array.array"\n' - '\n' - ' * "collections.deque"\n' - '\n' - ' * "list"\n' - '\n' - ' * "memoryview"\n' - '\n' - ' * "range"\n' - '\n' - ' * "tuple"\n' - '\n' - ' Note:\n' - '\n' - ' Subject values of type "str", "bytes", and "bytearray" do ' - 'not\n' - ' match sequence patterns.\n' - '\n' - '[3] In pattern matching, a mapping is defined as one of the ' - 'following:\n' - '\n' - ' * a class that inherits from "collections.abc.Mapping"\n' - '\n' - ' * a Python class that has been registered as\n' - ' "collections.abc.Mapping"\n' - '\n' - ' * a builtin class that has its (CPython) ' - '"Py_TPFLAGS_MAPPING"\n' - ' bit set\n' - '\n' - ' * a class that inherits from any of the above\n' - '\n' - ' The standard library classes "dict" and ' - '"types.MappingProxyType"\n' - ' are mappings.\n' - '\n' - '[4] A string literal appearing as the first statement in the ' - 'function\n' - ' body is transformed into the function’s "__doc__" attribute ' - 'and\n' - ' therefore the function’s *docstring*.\n' - '\n' - '[5] A string literal appearing as the first statement in the class\n' - ' body is transformed into the namespace’s "__doc__" item and\n' - ' therefore the class’s *docstring*.\n', - 'atom-identifiers': 'Identifiers (Names)\n' - '*******************\n' - '\n' - 'An identifier occurring as an atom is a name. See ' - 'section Identifiers\n' - 'and keywords for lexical definition and section Naming ' - 'and binding for\n' - 'documentation of naming and binding.\n' - '\n' - 'When the name is bound to an object, evaluation of the ' - 'atom yields\n' - 'that object. When a name is not bound, an attempt to ' - 'evaluate it\n' - 'raises a "NameError" exception.\n' - '\n' - '**Private name mangling:** When an identifier that ' - 'textually occurs in\n' - 'a class definition begins with two or more underscore ' - 'characters and\n' - 'does not end in two or more underscores, it is ' - 'considered a *private\n' - 'name* of that class. Private names are transformed to a ' - 'longer form\n' - 'before code is generated for them. The transformation ' - 'inserts the\n' - 'class name, with leading underscores removed and a ' - 'single underscore\n' - 'inserted, in front of the name. For example, the ' - 'identifier "__spam"\n' - 'occurring in a class named "Ham" will be transformed to ' - '"_Ham__spam".\n' - 'This transformation is independent of the syntactical ' - 'context in which\n' - 'the identifier is used. If the transformed name is ' - 'extremely long\n' - '(longer than 255 characters), implementation defined ' - 'truncation may\n' - 'happen. If the class name consists only of underscores, ' - 'no\n' - 'transformation is done.\n', - 'atom-literals': 'Literals\n' - '********\n' - '\n' - 'Python supports string and bytes literals and various ' - 'numeric\n' - 'literals:\n' - '\n' - ' literal ::= stringliteral | bytesliteral\n' - ' | integer | floatnumber | imagnumber\n' - '\n' - 'Evaluation of a literal yields an object of the given type ' - '(string,\n' - 'bytes, integer, floating point number, complex number) with ' - 'the given\n' - 'value. The value may be approximated in the case of ' - 'floating point\n' - 'and imaginary (complex) literals. See section Literals for ' - 'details.\n' - '\n' - 'All literals correspond to immutable data types, and hence ' - 'the\n' - 'object’s identity is less important than its value. ' - 'Multiple\n' - 'evaluations of literals with the same value (either the ' - 'same\n' - 'occurrence in the program text or a different occurrence) ' - 'may obtain\n' - 'the same object or a different object with the same ' - 'value.\n', - 'attribute-access': 'Customizing attribute access\n' - '****************************\n' - '\n' - 'The following methods can be defined to customize the ' - 'meaning of\n' - 'attribute access (use of, assignment to, or deletion of ' - '"x.name") for\n' - 'class instances.\n' - '\n' - 'object.__getattr__(self, name)\n' - '\n' - ' Called when the default attribute access fails with ' - 'an\n' - ' "AttributeError" (either "__getattribute__()" raises ' - 'an\n' - ' "AttributeError" because *name* is not an instance ' - 'attribute or an\n' - ' attribute in the class tree for "self"; or ' - '"__get__()" of a *name*\n' - ' property raises "AttributeError"). This method ' - 'should either\n' - ' return the (computed) attribute value or raise an ' - '"AttributeError"\n' - ' exception.\n' - '\n' - ' Note that if the attribute is found through the ' - 'normal mechanism,\n' - ' "__getattr__()" is not called. (This is an ' - 'intentional asymmetry\n' - ' between "__getattr__()" and "__setattr__()".) This is ' - 'done both for\n' - ' efficiency reasons and because otherwise ' - '"__getattr__()" would have\n' - ' no way to access other attributes of the instance. ' - 'Note that at\n' - ' least for instance variables, you can fake total ' - 'control by not\n' - ' inserting any values in the instance attribute ' - 'dictionary (but\n' - ' instead inserting them in another object). See the\n' - ' "__getattribute__()" method below for a way to ' - 'actually get total\n' - ' control over attribute access.\n' - '\n' - 'object.__getattribute__(self, name)\n' - '\n' - ' Called unconditionally to implement attribute ' - 'accesses for\n' - ' instances of the class. If the class also defines ' - '"__getattr__()",\n' - ' the latter will not be called unless ' - '"__getattribute__()" either\n' - ' calls it explicitly or raises an "AttributeError". ' - 'This method\n' - ' should return the (computed) attribute value or raise ' - 'an\n' - ' "AttributeError" exception. In order to avoid ' - 'infinite recursion in\n' - ' this method, its implementation should always call ' - 'the base class\n' - ' method with the same name to access any attributes it ' - 'needs, for\n' - ' example, "object.__getattribute__(self, name)".\n' - '\n' - ' Note:\n' - '\n' - ' This method may still be bypassed when looking up ' - 'special methods\n' - ' as the result of implicit invocation via language ' - 'syntax or\n' - ' built-in functions. See Special method lookup.\n' - '\n' - ' For certain sensitive attribute accesses, raises an ' - 'auditing event\n' - ' "object.__getattr__" with arguments "obj" and ' - '"name".\n' - '\n' - 'object.__setattr__(self, name, value)\n' - '\n' - ' Called when an attribute assignment is attempted. ' - 'This is called\n' - ' instead of the normal mechanism (i.e. store the value ' - 'in the\n' - ' instance dictionary). *name* is the attribute name, ' - '*value* is the\n' - ' value to be assigned to it.\n' - '\n' - ' If "__setattr__()" wants to assign to an instance ' - 'attribute, it\n' - ' should call the base class method with the same name, ' - 'for example,\n' - ' "object.__setattr__(self, name, value)".\n' - '\n' - ' For certain sensitive attribute assignments, raises ' - 'an auditing\n' - ' event "object.__setattr__" with arguments "obj", ' - '"name", "value".\n' - '\n' - 'object.__delattr__(self, name)\n' - '\n' - ' Like "__setattr__()" but for attribute deletion ' - 'instead of\n' - ' assignment. This should only be implemented if "del ' - 'obj.name" is\n' - ' meaningful for the object.\n' - '\n' - ' For certain sensitive attribute deletions, raises an ' - 'auditing event\n' - ' "object.__delattr__" with arguments "obj" and ' - '"name".\n' - '\n' - 'object.__dir__(self)\n' - '\n' - ' Called when "dir()" is called on the object. A ' - 'sequence must be\n' - ' returned. "dir()" converts the returned sequence to a ' - 'list and\n' - ' sorts it.\n' - '\n' - '\n' - 'Customizing module attribute access\n' - '===================================\n' - '\n' - 'Special names "__getattr__" and "__dir__" can be also ' - 'used to\n' - 'customize access to module attributes. The "__getattr__" ' - 'function at\n' - 'the module level should accept one argument which is the ' - 'name of an\n' - 'attribute and return the computed value or raise an ' - '"AttributeError".\n' - 'If an attribute is not found on a module object through ' - 'the normal\n' - 'lookup, i.e. "object.__getattribute__()", then ' - '"__getattr__" is\n' - 'searched in the module "__dict__" before raising an ' - '"AttributeError".\n' - 'If found, it is called with the attribute name and the ' - 'result is\n' - 'returned.\n' - '\n' - 'The "__dir__" function should accept no arguments, and ' - 'return a\n' - 'sequence of strings that represents the names accessible ' - 'on module. If\n' - 'present, this function overrides the standard "dir()" ' - 'search on a\n' - 'module.\n' - '\n' - 'For a more fine grained customization of the module ' - 'behavior (setting\n' - 'attributes, properties, etc.), one can set the ' - '"__class__" attribute\n' - 'of a module object to a subclass of "types.ModuleType". ' - 'For example:\n' - '\n' - ' import sys\n' - ' from types import ModuleType\n' - '\n' - ' class VerboseModule(ModuleType):\n' - ' def __repr__(self):\n' - " return f'Verbose {self.__name__}'\n" - '\n' - ' def __setattr__(self, attr, value):\n' - " print(f'Setting {attr}...')\n" - ' super().__setattr__(attr, value)\n' - '\n' - ' sys.modules[__name__].__class__ = VerboseModule\n' - '\n' - 'Note:\n' - '\n' - ' Defining module "__getattr__" and setting module ' - '"__class__" only\n' - ' affect lookups made using the attribute access syntax ' - '– directly\n' - ' accessing the module globals (whether by code within ' - 'the module, or\n' - ' via a reference to the module’s globals dictionary) is ' - 'unaffected.\n' - '\n' - 'Changed in version 3.5: "__class__" module attribute is ' - 'now writable.\n' - '\n' - 'New in version 3.7: "__getattr__" and "__dir__" module ' - 'attributes.\n' - '\n' - 'See also:\n' - '\n' - ' **PEP 562** - Module __getattr__ and __dir__\n' - ' Describes the "__getattr__" and "__dir__" functions ' - 'on modules.\n' - '\n' - '\n' - 'Implementing Descriptors\n' - '========================\n' - '\n' - 'The following methods only apply when an instance of the ' - 'class\n' - 'containing the method (a so-called *descriptor* class) ' - 'appears in an\n' - '*owner* class (the descriptor must be in either the ' - 'owner’s class\n' - 'dictionary or in the class dictionary for one of its ' - 'parents). In the\n' - 'examples below, “the attribute” refers to the attribute ' - 'whose name is\n' - 'the key of the property in the owner class’ "__dict__".\n' - '\n' - 'object.__get__(self, instance, owner=None)\n' - '\n' - ' Called to get the attribute of the owner class (class ' - 'attribute\n' - ' access) or of an instance of that class (instance ' - 'attribute\n' - ' access). The optional *owner* argument is the owner ' - 'class, while\n' - ' *instance* is the instance that the attribute was ' - 'accessed through,\n' - ' or "None" when the attribute is accessed through the ' - '*owner*.\n' - '\n' - ' This method should return the computed attribute ' - 'value or raise an\n' - ' "AttributeError" exception.\n' - '\n' - ' **PEP 252** specifies that "__get__()" is callable ' - 'with one or two\n' - ' arguments. Python’s own built-in descriptors support ' - 'this\n' - ' specification; however, it is likely that some ' - 'third-party tools\n' - ' have descriptors that require both arguments. ' - 'Python’s own\n' - ' "__getattribute__()" implementation always passes in ' - 'both arguments\n' - ' whether they are required or not.\n' - '\n' - 'object.__set__(self, instance, value)\n' - '\n' - ' Called to set the attribute on an instance *instance* ' - 'of the owner\n' - ' class to a new value, *value*.\n' - '\n' - ' Note, adding "__set__()" or "__delete__()" changes ' - 'the kind of\n' - ' descriptor to a “data descriptor”. See Invoking ' - 'Descriptors for\n' - ' more details.\n' - '\n' - 'object.__delete__(self, instance)\n' - '\n' - ' Called to delete the attribute on an instance ' - '*instance* of the\n' - ' owner class.\n' - '\n' - 'The attribute "__objclass__" is interpreted by the ' - '"inspect" module as\n' - 'specifying the class where this object was defined ' - '(setting this\n' - 'appropriately can assist in runtime introspection of ' - 'dynamic class\n' - 'attributes). For callables, it may indicate that an ' - 'instance of the\n' - 'given type (or a subclass) is expected or required as ' - 'the first\n' - 'positional argument (for example, CPython sets this ' - 'attribute for\n' - 'unbound methods that are implemented in C).\n' - '\n' - '\n' - 'Invoking Descriptors\n' - '====================\n' - '\n' - 'In general, a descriptor is an object attribute with ' - '“binding\n' - 'behavior”, one whose attribute access has been ' - 'overridden by methods\n' - 'in the descriptor protocol: "__get__()", "__set__()", ' - 'and\n' - '"__delete__()". If any of those methods are defined for ' - 'an object, it\n' - 'is said to be a descriptor.\n' - '\n' - 'The default behavior for attribute access is to get, ' - 'set, or delete\n' - 'the attribute from an object’s dictionary. For instance, ' - '"a.x" has a\n' - 'lookup chain starting with "a.__dict__[\'x\']", then\n' - '"type(a).__dict__[\'x\']", and continuing through the ' - 'base classes of\n' - '"type(a)" excluding metaclasses.\n' - '\n' - 'However, if the looked-up value is an object defining ' - 'one of the\n' - 'descriptor methods, then Python may override the default ' - 'behavior and\n' - 'invoke the descriptor method instead. Where this occurs ' - 'in the\n' - 'precedence chain depends on which descriptor methods ' - 'were defined and\n' - 'how they were called.\n' - '\n' - 'The starting point for descriptor invocation is a ' - 'binding, "a.x". How\n' - 'the arguments are assembled depends on "a":\n' - '\n' - 'Direct Call\n' - ' The simplest and least common call is when user code ' - 'directly\n' - ' invokes a descriptor method: "x.__get__(a)".\n' - '\n' - 'Instance Binding\n' - ' If binding to an object instance, "a.x" is ' - 'transformed into the\n' - ' call: "type(a).__dict__[\'x\'].__get__(a, type(a))".\n' - '\n' - 'Class Binding\n' - ' If binding to a class, "A.x" is transformed into the ' - 'call:\n' - ' "A.__dict__[\'x\'].__get__(None, A)".\n' - '\n' - 'Super Binding\n' - ' If "a" is an instance of "super", then the binding ' - '"super(B,\n' - ' obj).m()" searches "obj.__class__.__mro__" for the ' - 'base class "A"\n' - ' immediately following "B" and then invokes the ' - 'descriptor with the\n' - ' call: "A.__dict__[\'m\'].__get__(obj, ' - 'obj.__class__)".\n' - '\n' - 'For instance bindings, the precedence of descriptor ' - 'invocation depends\n' - 'on which descriptor methods are defined. A descriptor ' - 'can define any\n' - 'combination of "__get__()", "__set__()" and ' - '"__delete__()". If it\n' - 'does not define "__get__()", then accessing the ' - 'attribute will return\n' - 'the descriptor object itself unless there is a value in ' - 'the object’s\n' - 'instance dictionary. If the descriptor defines ' - '"__set__()" and/or\n' - '"__delete__()", it is a data descriptor; if it defines ' - 'neither, it is\n' - 'a non-data descriptor. Normally, data descriptors ' - 'define both\n' - '"__get__()" and "__set__()", while non-data descriptors ' - 'have just the\n' - '"__get__()" method. Data descriptors with "__get__()" ' - 'and "__set__()"\n' - '(and/or "__delete__()") defined always override a ' - 'redefinition in an\n' - 'instance dictionary. In contrast, non-data descriptors ' - 'can be\n' - 'overridden by instances.\n' - '\n' - 'Python methods (including those decorated with ' - '"@staticmethod" and\n' - '"@classmethod") are implemented as non-data ' - 'descriptors. Accordingly,\n' - 'instances can redefine and override methods. This ' - 'allows individual\n' - 'instances to acquire behaviors that differ from other ' - 'instances of the\n' - 'same class.\n' - '\n' - 'The "property()" function is implemented as a data ' - 'descriptor.\n' - 'Accordingly, instances cannot override the behavior of a ' - 'property.\n' - '\n' - '\n' - '__slots__\n' - '=========\n' - '\n' - '*__slots__* allow us to explicitly declare data members ' - '(like\n' - 'properties) and deny the creation of "__dict__" and ' - '*__weakref__*\n' - '(unless explicitly declared in *__slots__* or available ' - 'in a parent.)\n' - '\n' - 'The space saved over using "__dict__" can be ' - 'significant. Attribute\n' - 'lookup speed can be significantly improved as well.\n' - '\n' - 'object.__slots__\n' - '\n' - ' This class variable can be assigned a string, ' - 'iterable, or sequence\n' - ' of strings with variable names used by instances. ' - '*__slots__*\n' - ' reserves space for the declared variables and ' - 'prevents the\n' - ' automatic creation of "__dict__" and *__weakref__* ' - 'for each\n' - ' instance.\n' - '\n' - '\n' - 'Notes on using *__slots__*\n' - '--------------------------\n' - '\n' - '* When inheriting from a class without *__slots__*, the ' - '"__dict__" and\n' - ' *__weakref__* attribute of the instances will always ' - 'be accessible.\n' - '\n' - '* Without a "__dict__" variable, instances cannot be ' - 'assigned new\n' - ' variables not listed in the *__slots__* definition. ' - 'Attempts to\n' - ' assign to an unlisted variable name raises ' - '"AttributeError". If\n' - ' dynamic assignment of new variables is desired, then ' - 'add\n' - ' "\'__dict__\'" to the sequence of strings in the ' - '*__slots__*\n' - ' declaration.\n' - '\n' - '* Without a *__weakref__* variable for each instance, ' - 'classes defining\n' - ' *__slots__* do not support "weak references" to its ' - 'instances. If\n' - ' weak reference support is needed, then add ' - '"\'__weakref__\'" to the\n' - ' sequence of strings in the *__slots__* declaration.\n' - '\n' - '* *__slots__* are implemented at the class level by ' - 'creating\n' - ' descriptors for each variable name. As a result, ' - 'class attributes\n' - ' cannot be used to set default values for instance ' - 'variables defined\n' - ' by *__slots__*; otherwise, the class attribute would ' - 'overwrite the\n' - ' descriptor assignment.\n' - '\n' - '* The action of a *__slots__* declaration is not limited ' - 'to the class\n' - ' where it is defined. *__slots__* declared in parents ' - 'are available\n' - ' in child classes. However, child subclasses will get a ' - '"__dict__"\n' - ' and *__weakref__* unless they also define *__slots__* ' - '(which should\n' - ' only contain names of any *additional* slots).\n' - '\n' - '* If a class defines a slot also defined in a base ' - 'class, the instance\n' - ' variable defined by the base class slot is ' - 'inaccessible (except by\n' - ' retrieving its descriptor directly from the base ' - 'class). This\n' - ' renders the meaning of the program undefined. In the ' - 'future, a\n' - ' check may be added to prevent this.\n' - '\n' - '* Nonempty *__slots__* does not work for classes derived ' - 'from\n' - ' “variable-length” built-in types such as "int", ' - '"bytes" and "tuple".\n' - '\n' - '* Any non-string *iterable* may be assigned to ' - '*__slots__*.\n' - '\n' - '* If a "dictionary" is used to assign *__slots__*, the ' - 'dictionary keys\n' - ' will be used as the slot names. The values of the ' - 'dictionary can be\n' - ' used to provide per-attribute docstrings that will be ' - 'recognised by\n' - ' "inspect.getdoc()" and displayed in the output of ' - '"help()".\n' - '\n' - '* "__class__" assignment works only if both classes have ' - 'the same\n' - ' *__slots__*.\n' - '\n' - '* Multiple inheritance with multiple slotted parent ' - 'classes can be\n' - ' used, but only one parent is allowed to have ' - 'attributes created by\n' - ' slots (the other bases must have empty slot layouts) - ' - 'violations\n' - ' raise "TypeError".\n' - '\n' - '* If an *iterator* is used for *__slots__* then a ' - '*descriptor* is\n' - ' created for each of the iterator’s values. However, ' - 'the *__slots__*\n' - ' attribute will be an empty iterator.\n', - 'attribute-references': 'Attribute references\n' - '********************\n' - '\n' - 'An attribute reference is a primary followed by a ' - 'period and a name:\n' - '\n' - ' attributeref ::= primary "." identifier\n' - '\n' - 'The primary must evaluate to an object of a type ' - 'that supports\n' - 'attribute references, which most objects do. This ' - 'object is then\n' - 'asked to produce the attribute whose name is the ' - 'identifier. This\n' - 'production can be customized by overriding the ' - '"__getattr__()" method.\n' - 'If this attribute is not available, the exception ' - '"AttributeError" is\n' - 'raised. Otherwise, the type and value of the object ' - 'produced is\n' - 'determined by the object. Multiple evaluations of ' - 'the same attribute\n' - 'reference may yield different objects.\n', - 'augassign': 'Augmented assignment statements\n' - '*******************************\n' - '\n' - 'Augmented assignment is the combination, in a single statement, ' - 'of a\n' - 'binary operation and an assignment statement:\n' - '\n' - ' augmented_assignment_stmt ::= augtarget augop ' - '(expression_list | yield_expression)\n' - ' augtarget ::= identifier | attributeref | ' - 'subscription | slicing\n' - ' augop ::= "+=" | "-=" | "*=" | "@=" | ' - '"/=" | "//=" | "%=" | "**="\n' - ' | ">>=" | "<<=" | "&=" | "^=" | "|="\n' - '\n' - '(See section Primaries for the syntax definitions of the last ' - 'three\n' - 'symbols.)\n' - '\n' - 'An augmented assignment evaluates the target (which, unlike ' - 'normal\n' - 'assignment statements, cannot be an unpacking) and the ' - 'expression\n' - 'list, performs the binary operation specific to the type of ' - 'assignment\n' - 'on the two operands, and assigns the result to the original ' - 'target.\n' - 'The target is only evaluated once.\n' - '\n' - 'An augmented assignment expression like "x += 1" can be ' - 'rewritten as\n' - '"x = x + 1" to achieve a similar, but not exactly equal effect. ' - 'In the\n' - 'augmented version, "x" is only evaluated once. Also, when ' - 'possible,\n' - 'the actual operation is performed *in-place*, meaning that ' - 'rather than\n' - 'creating a new object and assigning that to the target, the old ' - 'object\n' - 'is modified instead.\n' - '\n' - 'Unlike normal assignments, augmented assignments evaluate the ' - 'left-\n' - 'hand side *before* evaluating the right-hand side. For ' - 'example, "a[i]\n' - '+= f(x)" first looks-up "a[i]", then it evaluates "f(x)" and ' - 'performs\n' - 'the addition, and lastly, it writes the result back to "a[i]".\n' - '\n' - 'With the exception of assigning to tuples and multiple targets ' - 'in a\n' - 'single statement, the assignment done by augmented assignment\n' - 'statements is handled the same way as normal assignments. ' - 'Similarly,\n' - 'with the exception of the possible *in-place* behavior, the ' - 'binary\n' - 'operation performed by augmented assignment is the same as the ' - 'normal\n' - 'binary operations.\n' - '\n' - 'For targets which are attribute references, the same caveat ' - 'about\n' - 'class and instance attributes applies as for regular ' - 'assignments.\n', - 'await': 'Await expression\n' - '****************\n' - '\n' - 'Suspend the execution of *coroutine* on an *awaitable* object. Can\n' - 'only be used inside a *coroutine function*.\n' - '\n' - ' await_expr ::= "await" primary\n' - '\n' - 'New in version 3.5.\n', - 'binary': 'Binary arithmetic operations\n' - '****************************\n' - '\n' - 'The binary arithmetic operations have the conventional priority\n' - 'levels. Note that some of these operations also apply to certain ' - 'non-\n' - 'numeric types. Apart from the power operator, there are only two\n' - 'levels, one for multiplicative operators and one for additive\n' - 'operators:\n' - '\n' - ' m_expr ::= u_expr | m_expr "*" u_expr | m_expr "@" m_expr |\n' - ' m_expr "//" u_expr | m_expr "/" u_expr |\n' - ' m_expr "%" u_expr\n' - ' a_expr ::= m_expr | a_expr "+" m_expr | a_expr "-" m_expr\n' - '\n' - 'The "*" (multiplication) operator yields the product of its ' - 'arguments.\n' - 'The arguments must either both be numbers, or one argument must be ' - 'an\n' - 'integer and the other must be a sequence. In the former case, the\n' - 'numbers are converted to a common type and then multiplied ' - 'together.\n' - 'In the latter case, sequence repetition is performed; a negative\n' - 'repetition factor yields an empty sequence.\n' - '\n' - 'This operation can be customized using the special "__mul__()" ' - 'and\n' - '"__rmul__()" methods.\n' - '\n' - 'The "@" (at) operator is intended to be used for matrix\n' - 'multiplication. No builtin Python types implement this operator.\n' - '\n' - 'New in version 3.5.\n' - '\n' - 'The "/" (division) and "//" (floor division) operators yield the\n' - 'quotient of their arguments. The numeric arguments are first\n' - 'converted to a common type. Division of integers yields a float, ' - 'while\n' - 'floor division of integers results in an integer; the result is ' - 'that\n' - 'of mathematical division with the ‘floor’ function applied to the\n' - 'result. Division by zero raises the "ZeroDivisionError" ' - 'exception.\n' - '\n' - 'This operation can be customized using the special "__truediv__()" ' - 'and\n' - '"__floordiv__()" methods.\n' - '\n' - 'The "%" (modulo) operator yields the remainder from the division ' - 'of\n' - 'the first argument by the second. The numeric arguments are ' - 'first\n' - 'converted to a common type. A zero right argument raises the\n' - '"ZeroDivisionError" exception. The arguments may be floating ' - 'point\n' - 'numbers, e.g., "3.14%0.7" equals "0.34" (since "3.14" equals ' - '"4*0.7 +\n' - '0.34".) The modulo operator always yields a result with the same ' - 'sign\n' - 'as its second operand (or zero); the absolute value of the result ' - 'is\n' - 'strictly smaller than the absolute value of the second operand ' - '[1].\n' - '\n' - 'The floor division and modulo operators are connected by the ' - 'following\n' - 'identity: "x == (x//y)*y + (x%y)". Floor division and modulo are ' - 'also\n' - 'connected with the built-in function "divmod()": "divmod(x, y) ==\n' - '(x//y, x%y)". [2].\n' - '\n' - 'In addition to performing the modulo operation on numbers, the ' - '"%"\n' - 'operator is also overloaded by string objects to perform ' - 'old-style\n' - 'string formatting (also known as interpolation). The syntax for\n' - 'string formatting is described in the Python Library Reference,\n' - 'section printf-style String Formatting.\n' - '\n' - 'The *modulo* operation can be customized using the special ' - '"__mod__()"\n' - 'method.\n' - '\n' - 'The floor division operator, the modulo operator, and the ' - '"divmod()"\n' - 'function are not defined for complex numbers. Instead, convert to ' - 'a\n' - 'floating point number using the "abs()" function if appropriate.\n' - '\n' - 'The "+" (addition) operator yields the sum of its arguments. The\n' - 'arguments must either both be numbers or both be sequences of the ' - 'same\n' - 'type. In the former case, the numbers are converted to a common ' - 'type\n' - 'and then added together. In the latter case, the sequences are\n' - 'concatenated.\n' - '\n' - 'This operation can be customized using the special "__add__()" ' - 'and\n' - '"__radd__()" methods.\n' - '\n' - 'The "-" (subtraction) operator yields the difference of its ' - 'arguments.\n' - 'The numeric arguments are first converted to a common type.\n' - '\n' - 'This operation can be customized using the special "__sub__()" ' - 'method.\n', - 'bitwise': 'Binary bitwise operations\n' - '*************************\n' - '\n' - 'Each of the three bitwise operations has a different priority ' - 'level:\n' - '\n' - ' and_expr ::= shift_expr | and_expr "&" shift_expr\n' - ' xor_expr ::= and_expr | xor_expr "^" and_expr\n' - ' or_expr ::= xor_expr | or_expr "|" xor_expr\n' - '\n' - 'The "&" operator yields the bitwise AND of its arguments, which ' - 'must\n' - 'be integers or one of them must be a custom object overriding\n' - '"__and__()" or "__rand__()" special methods.\n' - '\n' - 'The "^" operator yields the bitwise XOR (exclusive OR) of its\n' - 'arguments, which must be integers or one of them must be a ' - 'custom\n' - 'object overriding "__xor__()" or "__rxor__()" special methods.\n' - '\n' - 'The "|" operator yields the bitwise (inclusive) OR of its ' - 'arguments,\n' - 'which must be integers or one of them must be a custom object\n' - 'overriding "__or__()" or "__ror__()" special methods.\n', - 'bltin-code-objects': 'Code Objects\n' - '************\n' - '\n' - 'Code objects are used by the implementation to ' - 'represent “pseudo-\n' - 'compiled” executable Python code such as a function ' - 'body. They differ\n' - 'from function objects because they don’t contain a ' - 'reference to their\n' - 'global execution environment. Code objects are ' - 'returned by the built-\n' - 'in "compile()" function and can be extracted from ' - 'function objects\n' - 'through their "__code__" attribute. See also the ' - '"code" module.\n' - '\n' - 'Accessing "__code__" raises an auditing event ' - '"object.__getattr__"\n' - 'with arguments "obj" and ""__code__"".\n' - '\n' - 'A code object can be executed or evaluated by passing ' - 'it (instead of a\n' - 'source string) to the "exec()" or "eval()" built-in ' - 'functions.\n' - '\n' - 'See The standard type hierarchy for more ' - 'information.\n', - 'bltin-ellipsis-object': 'The Ellipsis Object\n' - '*******************\n' - '\n' - 'This object is commonly used by slicing (see ' - 'Slicings). It supports\n' - 'no special operations. There is exactly one ' - 'ellipsis object, named\n' - '"Ellipsis" (a built-in name). "type(Ellipsis)()" ' - 'produces the\n' - '"Ellipsis" singleton.\n' - '\n' - 'It is written as "Ellipsis" or "...".\n', - 'bltin-null-object': 'The Null Object\n' - '***************\n' - '\n' - 'This object is returned by functions that don’t ' - 'explicitly return a\n' - 'value. It supports no special operations. There is ' - 'exactly one null\n' - 'object, named "None" (a built-in name). "type(None)()" ' - 'produces the\n' - 'same singleton.\n' - '\n' - 'It is written as "None".\n', - 'bltin-type-objects': 'Type Objects\n' - '************\n' - '\n' - 'Type objects represent the various object types. An ' - 'object’s type is\n' - 'accessed by the built-in function "type()". There are ' - 'no special\n' - 'operations on types. The standard module "types" ' - 'defines names for\n' - 'all standard built-in types.\n' - '\n' - 'Types are written like this: "<class \'int\'>".\n', - 'booleans': 'Boolean operations\n' - '******************\n' - '\n' - ' or_test ::= and_test | or_test "or" and_test\n' - ' and_test ::= not_test | and_test "and" not_test\n' - ' not_test ::= comparison | "not" not_test\n' - '\n' - 'In the context of Boolean operations, and also when expressions ' - 'are\n' - 'used by control flow statements, the following values are ' - 'interpreted\n' - 'as false: "False", "None", numeric zero of all types, and empty\n' - 'strings and containers (including strings, tuples, lists,\n' - 'dictionaries, sets and frozensets). All other values are ' - 'interpreted\n' - 'as true. User-defined objects can customize their truth value ' - 'by\n' - 'providing a "__bool__()" method.\n' - '\n' - 'The operator "not" yields "True" if its argument is false, ' - '"False"\n' - 'otherwise.\n' - '\n' - 'The expression "x and y" first evaluates *x*; if *x* is false, ' - 'its\n' - 'value is returned; otherwise, *y* is evaluated and the resulting ' - 'value\n' - 'is returned.\n' - '\n' - 'The expression "x or y" first evaluates *x*; if *x* is true, its ' - 'value\n' - 'is returned; otherwise, *y* is evaluated and the resulting value ' - 'is\n' - 'returned.\n' - '\n' - 'Note that neither "and" nor "or" restrict the value and type ' - 'they\n' - 'return to "False" and "True", but rather return the last ' - 'evaluated\n' - 'argument. This is sometimes useful, e.g., if "s" is a string ' - 'that\n' - 'should be replaced by a default value if it is empty, the ' - 'expression\n' - '"s or \'foo\'" yields the desired value. Because "not" has to ' - 'create a\n' - 'new value, it returns a boolean value regardless of the type of ' - 'its\n' - 'argument (for example, "not \'foo\'" produces "False" rather ' - 'than "\'\'".)\n', - 'break': 'The "break" statement\n' - '*********************\n' - '\n' - ' break_stmt ::= "break"\n' - '\n' - '"break" may only occur syntactically nested in a "for" or "while"\n' - 'loop, but not nested in a function or class definition within that\n' - 'loop.\n' - '\n' - 'It terminates the nearest enclosing loop, skipping the optional ' - '"else"\n' - 'clause if the loop has one.\n' - '\n' - 'If a "for" loop is terminated by "break", the loop control target\n' - 'keeps its current value.\n' - '\n' - 'When "break" passes control out of a "try" statement with a ' - '"finally"\n' - 'clause, that "finally" clause is executed before really leaving ' - 'the\n' - 'loop.\n', - 'callable-types': 'Emulating callable objects\n' - '**************************\n' - '\n' - 'object.__call__(self[, args...])\n' - '\n' - ' Called when the instance is “called” as a function; if ' - 'this method\n' - ' is defined, "x(arg1, arg2, ...)" roughly translates to\n' - ' "type(x).__call__(x, arg1, ...)".\n', - 'calls': 'Calls\n' - '*****\n' - '\n' - 'A call calls a callable object (e.g., a *function*) with a ' - 'possibly\n' - 'empty series of *arguments*:\n' - '\n' - ' call ::= primary "(" [argument_list [","] | ' - 'comprehension] ")"\n' - ' argument_list ::= positional_arguments ["," ' - 'starred_and_keywords]\n' - ' ["," keywords_arguments]\n' - ' | starred_and_keywords ["," ' - 'keywords_arguments]\n' - ' | keywords_arguments\n' - ' positional_arguments ::= positional_item ("," positional_item)*\n' - ' positional_item ::= assignment_expression | "*" expression\n' - ' starred_and_keywords ::= ("*" expression | keyword_item)\n' - ' ("," "*" expression | "," ' - 'keyword_item)*\n' - ' keywords_arguments ::= (keyword_item | "**" expression)\n' - ' ("," keyword_item | "," "**" ' - 'expression)*\n' - ' keyword_item ::= identifier "=" expression\n' - '\n' - 'An optional trailing comma may be present after the positional and\n' - 'keyword arguments but does not affect the semantics.\n' - '\n' - 'The primary must evaluate to a callable object (user-defined\n' - 'functions, built-in functions, methods of built-in objects, class\n' - 'objects, methods of class instances, and all objects having a\n' - '"__call__()" method are callable). All argument expressions are\n' - 'evaluated before the call is attempted. Please refer to section\n' - 'Function definitions for the syntax of formal *parameter* lists.\n' - '\n' - 'If keyword arguments are present, they are first converted to\n' - 'positional arguments, as follows. First, a list of unfilled slots ' - 'is\n' - 'created for the formal parameters. If there are N positional\n' - 'arguments, they are placed in the first N slots. Next, for each\n' - 'keyword argument, the identifier is used to determine the\n' - 'corresponding slot (if the identifier is the same as the first ' - 'formal\n' - 'parameter name, the first slot is used, and so on). If the slot ' - 'is\n' - 'already filled, a "TypeError" exception is raised. Otherwise, the\n' - 'value of the argument is placed in the slot, filling it (even if ' - 'the\n' - 'expression is "None", it fills the slot). When all arguments have\n' - 'been processed, the slots that are still unfilled are filled with ' - 'the\n' - 'corresponding default value from the function definition. ' - '(Default\n' - 'values are calculated, once, when the function is defined; thus, a\n' - 'mutable object such as a list or dictionary used as default value ' - 'will\n' - 'be shared by all calls that don’t specify an argument value for ' - 'the\n' - 'corresponding slot; this should usually be avoided.) If there are ' - 'any\n' - 'unfilled slots for which no default value is specified, a ' - '"TypeError"\n' - 'exception is raised. Otherwise, the list of filled slots is used ' - 'as\n' - 'the argument list for the call.\n' - '\n' - '**CPython implementation detail:** An implementation may provide\n' - 'built-in functions whose positional parameters do not have names, ' - 'even\n' - 'if they are ‘named’ for the purpose of documentation, and which\n' - 'therefore cannot be supplied by keyword. In CPython, this is the ' - 'case\n' - 'for functions implemented in C that use "PyArg_ParseTuple()" to ' - 'parse\n' - 'their arguments.\n' - '\n' - 'If there are more positional arguments than there are formal ' - 'parameter\n' - 'slots, a "TypeError" exception is raised, unless a formal ' - 'parameter\n' - 'using the syntax "*identifier" is present; in this case, that ' - 'formal\n' - 'parameter receives a tuple containing the excess positional ' - 'arguments\n' - '(or an empty tuple if there were no excess positional arguments).\n' - '\n' - 'If any keyword argument does not correspond to a formal parameter\n' - 'name, a "TypeError" exception is raised, unless a formal parameter\n' - 'using the syntax "**identifier" is present; in this case, that ' - 'formal\n' - 'parameter receives a dictionary containing the excess keyword\n' - 'arguments (using the keywords as keys and the argument values as\n' - 'corresponding values), or a (new) empty dictionary if there were ' - 'no\n' - 'excess keyword arguments.\n' - '\n' - 'If the syntax "*expression" appears in the function call, ' - '"expression"\n' - 'must evaluate to an *iterable*. Elements from these iterables are\n' - 'treated as if they were additional positional arguments. For the ' - 'call\n' - '"f(x1, x2, *y, x3, x4)", if *y* evaluates to a sequence *y1*, …, ' - '*yM*,\n' - 'this is equivalent to a call with M+4 positional arguments *x1*, ' - '*x2*,\n' - '*y1*, …, *yM*, *x3*, *x4*.\n' - '\n' - 'A consequence of this is that although the "*expression" syntax ' - 'may\n' - 'appear *after* explicit keyword arguments, it is processed ' - '*before*\n' - 'the keyword arguments (and any "**expression" arguments – see ' - 'below).\n' - 'So:\n' - '\n' - ' >>> def f(a, b):\n' - ' ... print(a, b)\n' - ' ...\n' - ' >>> f(b=1, *(2,))\n' - ' 2 1\n' - ' >>> f(a=1, *(2,))\n' - ' Traceback (most recent call last):\n' - ' File "<stdin>", line 1, in <module>\n' - " TypeError: f() got multiple values for keyword argument 'a'\n" - ' >>> f(1, *(2,))\n' - ' 1 2\n' - '\n' - 'It is unusual for both keyword arguments and the "*expression" ' - 'syntax\n' - 'to be used in the same call, so in practice this confusion does ' - 'not\n' - 'arise.\n' - '\n' - 'If the syntax "**expression" appears in the function call,\n' - '"expression" must evaluate to a *mapping*, the contents of which ' - 'are\n' - 'treated as additional keyword arguments. If a keyword is already\n' - 'present (as an explicit keyword argument, or from another ' - 'unpacking),\n' - 'a "TypeError" exception is raised.\n' - '\n' - 'Formal parameters using the syntax "*identifier" or "**identifier"\n' - 'cannot be used as positional argument slots or as keyword argument\n' - 'names.\n' - '\n' - 'Changed in version 3.5: Function calls accept any number of "*" ' - 'and\n' - '"**" unpackings, positional arguments may follow iterable ' - 'unpackings\n' - '("*"), and keyword arguments may follow dictionary unpackings ' - '("**").\n' - 'Originally proposed by **PEP 448**.\n' - '\n' - 'A call always returns some value, possibly "None", unless it raises ' - 'an\n' - 'exception. How this value is computed depends on the type of the\n' - 'callable object.\n' - '\n' - 'If it is—\n' - '\n' - 'a user-defined function:\n' - ' The code block for the function is executed, passing it the\n' - ' argument list. The first thing the code block will do is bind ' - 'the\n' - ' formal parameters to the arguments; this is described in ' - 'section\n' - ' Function definitions. When the code block executes a "return"\n' - ' statement, this specifies the return value of the function ' - 'call.\n' - '\n' - 'a built-in function or method:\n' - ' The result is up to the interpreter; see Built-in Functions for ' - 'the\n' - ' descriptions of built-in functions and methods.\n' - '\n' - 'a class object:\n' - ' A new instance of that class is returned.\n' - '\n' - 'a class instance method:\n' - ' The corresponding user-defined function is called, with an ' - 'argument\n' - ' list that is one longer than the argument list of the call: the\n' - ' instance becomes the first argument.\n' - '\n' - 'a class instance:\n' - ' The class must define a "__call__()" method; the effect is then ' - 'the\n' - ' same as if that method was called.\n', - 'class': 'Class definitions\n' - '*****************\n' - '\n' - 'A class definition defines a class object (see section The ' - 'standard\n' - 'type hierarchy):\n' - '\n' - ' classdef ::= [decorators] "class" classname [inheritance] ":" ' - 'suite\n' - ' inheritance ::= "(" [argument_list] ")"\n' - ' classname ::= identifier\n' - '\n' - 'A class definition is an executable statement. The inheritance ' - 'list\n' - 'usually gives a list of base classes (see Metaclasses for more\n' - 'advanced uses), so each item in the list should evaluate to a ' - 'class\n' - 'object which allows subclassing. Classes without an inheritance ' - 'list\n' - 'inherit, by default, from the base class "object"; hence,\n' - '\n' - ' class Foo:\n' - ' pass\n' - '\n' - 'is equivalent to\n' - '\n' - ' class Foo(object):\n' - ' pass\n' - '\n' - 'The class’s suite is then executed in a new execution frame (see\n' - 'Naming and binding), using a newly created local namespace and the\n' - 'original global namespace. (Usually, the suite contains mostly\n' - 'function definitions.) When the class’s suite finishes execution, ' - 'its\n' - 'execution frame is discarded but its local namespace is saved. [5] ' - 'A\n' - 'class object is then created using the inheritance list for the ' - 'base\n' - 'classes and the saved local namespace for the attribute ' - 'dictionary.\n' - 'The class name is bound to this class object in the original local\n' - 'namespace.\n' - '\n' - 'The order in which attributes are defined in the class body is\n' - 'preserved in the new class’s "__dict__". Note that this is ' - 'reliable\n' - 'only right after the class is created and only for classes that ' - 'were\n' - 'defined using the definition syntax.\n' - '\n' - 'Class creation can be customized heavily using metaclasses.\n' - '\n' - 'Classes can also be decorated: just like when decorating ' - 'functions,\n' - '\n' - ' @f1(arg)\n' - ' @f2\n' - ' class Foo: pass\n' - '\n' - 'is roughly equivalent to\n' - '\n' - ' class Foo: pass\n' - ' Foo = f1(arg)(f2(Foo))\n' - '\n' - 'The evaluation rules for the decorator expressions are the same as ' - 'for\n' - 'function decorators. The result is then bound to the class name.\n' - '\n' - 'Changed in version 3.9: Classes may be decorated with any valid\n' - '"assignment_expression". Previously, the grammar was much more\n' - 'restrictive; see **PEP 614** for details.\n' - '\n' - '**Programmer’s note:** Variables defined in the class definition ' - 'are\n' - 'class attributes; they are shared by instances. Instance ' - 'attributes\n' - 'can be set in a method with "self.name = value". Both class and\n' - 'instance attributes are accessible through the notation ' - '“"self.name"”,\n' - 'and an instance attribute hides a class attribute with the same ' - 'name\n' - 'when accessed in this way. Class attributes can be used as ' - 'defaults\n' - 'for instance attributes, but using mutable values there can lead ' - 'to\n' - 'unexpected results. Descriptors can be used to create instance\n' - 'variables with different implementation details.\n' - '\n' - 'See also:\n' - '\n' - ' **PEP 3115** - Metaclasses in Python 3000\n' - ' The proposal that changed the declaration of metaclasses to ' - 'the\n' - ' current syntax, and the semantics for how classes with\n' - ' metaclasses are constructed.\n' - '\n' - ' **PEP 3129** - Class Decorators\n' - ' The proposal that added class decorators. Function and ' - 'method\n' - ' decorators were introduced in **PEP 318**.\n', - 'comparisons': 'Comparisons\n' - '***********\n' - '\n' - 'Unlike C, all comparison operations in Python have the same ' - 'priority,\n' - 'which is lower than that of any arithmetic, shifting or ' - 'bitwise\n' - 'operation. Also unlike C, expressions like "a < b < c" have ' - 'the\n' - 'interpretation that is conventional in mathematics:\n' - '\n' - ' comparison ::= or_expr (comp_operator or_expr)*\n' - ' comp_operator ::= "<" | ">" | "==" | ">=" | "<=" | "!="\n' - ' | "is" ["not"] | ["not"] "in"\n' - '\n' - 'Comparisons yield boolean values: "True" or "False". Custom ' - '*rich\n' - 'comparison methods* may return non-boolean values. In this ' - 'case Python\n' - 'will call "bool()" on such value in boolean contexts.\n' - '\n' - 'Comparisons can be chained arbitrarily, e.g., "x < y <= z" ' - 'is\n' - 'equivalent to "x < y and y <= z", except that "y" is ' - 'evaluated only\n' - 'once (but in both cases "z" is not evaluated at all when "x < ' - 'y" is\n' - 'found to be false).\n' - '\n' - 'Formally, if *a*, *b*, *c*, …, *y*, *z* are expressions and ' - '*op1*,\n' - '*op2*, …, *opN* are comparison operators, then "a op1 b op2 c ' - '... y\n' - 'opN z" is equivalent to "a op1 b and b op2 c and ... y opN ' - 'z", except\n' - 'that each expression is evaluated at most once.\n' - '\n' - 'Note that "a op1 b op2 c" doesn’t imply any kind of ' - 'comparison between\n' - '*a* and *c*, so that, e.g., "x < y > z" is perfectly legal ' - '(though\n' - 'perhaps not pretty).\n' - '\n' - '\n' - 'Value comparisons\n' - '=================\n' - '\n' - 'The operators "<", ">", "==", ">=", "<=", and "!=" compare ' - 'the values\n' - 'of two objects. The objects do not need to have the same ' - 'type.\n' - '\n' - 'Chapter Objects, values and types states that objects have a ' - 'value (in\n' - 'addition to type and identity). The value of an object is a ' - 'rather\n' - 'abstract notion in Python: For example, there is no canonical ' - 'access\n' - 'method for an object’s value. Also, there is no requirement ' - 'that the\n' - 'value of an object should be constructed in a particular way, ' - 'e.g.\n' - 'comprised of all its data attributes. Comparison operators ' - 'implement a\n' - 'particular notion of what the value of an object is. One can ' - 'think of\n' - 'them as defining the value of an object indirectly, by means ' - 'of their\n' - 'comparison implementation.\n' - '\n' - 'Because all types are (direct or indirect) subtypes of ' - '"object", they\n' - 'inherit the default comparison behavior from "object". Types ' - 'can\n' - 'customize their comparison behavior by implementing *rich ' - 'comparison\n' - 'methods* like "__lt__()", described in Basic customization.\n' - '\n' - 'The default behavior for equality comparison ("==" and "!=") ' - 'is based\n' - 'on the identity of the objects. Hence, equality comparison ' - 'of\n' - 'instances with the same identity results in equality, and ' - 'equality\n' - 'comparison of instances with different identities results in\n' - 'inequality. A motivation for this default behavior is the ' - 'desire that\n' - 'all objects should be reflexive (i.e. "x is y" implies "x == ' - 'y").\n' - '\n' - 'A default order comparison ("<", ">", "<=", and ">=") is not ' - 'provided;\n' - 'an attempt raises "TypeError". A motivation for this default ' - 'behavior\n' - 'is the lack of a similar invariant as for equality.\n' - '\n' - 'The behavior of the default equality comparison, that ' - 'instances with\n' - 'different identities are always unequal, may be in contrast ' - 'to what\n' - 'types will need that have a sensible definition of object ' - 'value and\n' - 'value-based equality. Such types will need to customize ' - 'their\n' - 'comparison behavior, and in fact, a number of built-in types ' - 'have done\n' - 'that.\n' - '\n' - 'The following list describes the comparison behavior of the ' - 'most\n' - 'important built-in types.\n' - '\n' - '* Numbers of built-in numeric types (Numeric Types — int, ' - 'float,\n' - ' complex) and of the standard library types ' - '"fractions.Fraction" and\n' - ' "decimal.Decimal" can be compared within and across their ' - 'types,\n' - ' with the restriction that complex numbers do not support ' - 'order\n' - ' comparison. Within the limits of the types involved, they ' - 'compare\n' - ' mathematically (algorithmically) correct without loss of ' - 'precision.\n' - '\n' - ' The not-a-number values "float(\'NaN\')" and ' - '"decimal.Decimal(\'NaN\')"\n' - ' are special. Any ordered comparison of a number to a ' - 'not-a-number\n' - ' value is false. A counter-intuitive implication is that ' - 'not-a-number\n' - ' values are not equal to themselves. For example, if "x =\n' - ' float(\'NaN\')", "3 < x", "x < 3" and "x == x" are all ' - 'false, while "x\n' - ' != x" is true. This behavior is compliant with IEEE 754.\n' - '\n' - '* "None" and "NotImplemented" are singletons. **PEP 8** ' - 'advises that\n' - ' comparisons for singletons should always be done with "is" ' - 'or "is\n' - ' not", never the equality operators.\n' - '\n' - '* Binary sequences (instances of "bytes" or "bytearray") can ' - 'be\n' - ' compared within and across their types. They compare\n' - ' lexicographically using the numeric values of their ' - 'elements.\n' - '\n' - '* Strings (instances of "str") compare lexicographically ' - 'using the\n' - ' numerical Unicode code points (the result of the built-in ' - 'function\n' - ' "ord()") of their characters. [3]\n' - '\n' - ' Strings and binary sequences cannot be directly compared.\n' - '\n' - '* Sequences (instances of "tuple", "list", or "range") can be ' - 'compared\n' - ' only within each of their types, with the restriction that ' - 'ranges do\n' - ' not support order comparison. Equality comparison across ' - 'these\n' - ' types results in inequality, and ordering comparison across ' - 'these\n' - ' types raises "TypeError".\n' - '\n' - ' Sequences compare lexicographically using comparison of\n' - ' corresponding elements. The built-in containers typically ' - 'assume\n' - ' identical objects are equal to themselves. That lets them ' - 'bypass\n' - ' equality tests for identical objects to improve performance ' - 'and to\n' - ' maintain their internal invariants.\n' - '\n' - ' Lexicographical comparison between built-in collections ' - 'works as\n' - ' follows:\n' - '\n' - ' * For two collections to compare equal, they must be of the ' - 'same\n' - ' type, have the same length, and each pair of ' - 'corresponding\n' - ' elements must compare equal (for example, "[1,2] == ' - '(1,2)" is\n' - ' false because the type is not the same).\n' - '\n' - ' * Collections that support order comparison are ordered the ' - 'same as\n' - ' their first unequal elements (for example, "[1,2,x] <= ' - '[1,2,y]"\n' - ' has the same value as "x <= y"). If a corresponding ' - 'element does\n' - ' not exist, the shorter collection is ordered first (for ' - 'example,\n' - ' "[1,2] < [1,2,3]" is true).\n' - '\n' - '* Mappings (instances of "dict") compare equal if and only if ' - 'they\n' - ' have equal *(key, value)* pairs. Equality comparison of the ' - 'keys and\n' - ' values enforces reflexivity.\n' - '\n' - ' Order comparisons ("<", ">", "<=", and ">=") raise ' - '"TypeError".\n' - '\n' - '* Sets (instances of "set" or "frozenset") can be compared ' - 'within and\n' - ' across their types.\n' - '\n' - ' They define order comparison operators to mean subset and ' - 'superset\n' - ' tests. Those relations do not define total orderings (for ' - 'example,\n' - ' the two sets "{1,2}" and "{2,3}" are not equal, nor subsets ' - 'of one\n' - ' another, nor supersets of one another). Accordingly, sets ' - 'are not\n' - ' appropriate arguments for functions which depend on total ' - 'ordering\n' - ' (for example, "min()", "max()", and "sorted()" produce ' - 'undefined\n' - ' results given a list of sets as inputs).\n' - '\n' - ' Comparison of sets enforces reflexivity of its elements.\n' - '\n' - '* Most other built-in types have no comparison methods ' - 'implemented, so\n' - ' they inherit the default comparison behavior.\n' - '\n' - 'User-defined classes that customize their comparison behavior ' - 'should\n' - 'follow some consistency rules, if possible:\n' - '\n' - '* Equality comparison should be reflexive. In other words, ' - 'identical\n' - ' objects should compare equal:\n' - '\n' - ' "x is y" implies "x == y"\n' - '\n' - '* Comparison should be symmetric. In other words, the ' - 'following\n' - ' expressions should have the same result:\n' - '\n' - ' "x == y" and "y == x"\n' - '\n' - ' "x != y" and "y != x"\n' - '\n' - ' "x < y" and "y > x"\n' - '\n' - ' "x <= y" and "y >= x"\n' - '\n' - '* Comparison should be transitive. The following ' - '(non-exhaustive)\n' - ' examples illustrate that:\n' - '\n' - ' "x > y and y > z" implies "x > z"\n' - '\n' - ' "x < y and y <= z" implies "x < z"\n' - '\n' - '* Inverse comparison should result in the boolean negation. ' - 'In other\n' - ' words, the following expressions should have the same ' - 'result:\n' - '\n' - ' "x == y" and "not x != y"\n' - '\n' - ' "x < y" and "not x >= y" (for total ordering)\n' - '\n' - ' "x > y" and "not x <= y" (for total ordering)\n' - '\n' - ' The last two expressions apply to totally ordered ' - 'collections (e.g.\n' - ' to sequences, but not to sets or mappings). See also the\n' - ' "total_ordering()" decorator.\n' - '\n' - '* The "hash()" result should be consistent with equality. ' - 'Objects that\n' - ' are equal should either have the same hash value, or be ' - 'marked as\n' - ' unhashable.\n' - '\n' - 'Python does not enforce these consistency rules. In fact, ' - 'the\n' - 'not-a-number values are an example for not following these ' - 'rules.\n' - '\n' - '\n' - 'Membership test operations\n' - '==========================\n' - '\n' - 'The operators "in" and "not in" test for membership. "x in ' - 's"\n' - 'evaluates to "True" if *x* is a member of *s*, and "False" ' - 'otherwise.\n' - '"x not in s" returns the negation of "x in s". All built-in ' - 'sequences\n' - 'and set types support this as well as dictionary, for which ' - '"in" tests\n' - 'whether the dictionary has a given key. For container types ' - 'such as\n' - 'list, tuple, set, frozenset, dict, or collections.deque, the\n' - 'expression "x in y" is equivalent to "any(x is e or x == e ' - 'for e in\n' - 'y)".\n' - '\n' - 'For the string and bytes types, "x in y" is "True" if and ' - 'only if *x*\n' - 'is a substring of *y*. An equivalent test is "y.find(x) != ' - '-1".\n' - 'Empty strings are always considered to be a substring of any ' - 'other\n' - 'string, so """ in "abc"" will return "True".\n' - '\n' - 'For user-defined classes which define the "__contains__()" ' - 'method, "x\n' - 'in y" returns "True" if "y.__contains__(x)" returns a true ' - 'value, and\n' - '"False" otherwise.\n' - '\n' - 'For user-defined classes which do not define "__contains__()" ' - 'but do\n' - 'define "__iter__()", "x in y" is "True" if some value "z", ' - 'for which\n' - 'the expression "x is z or x == z" is true, is produced while ' - 'iterating\n' - 'over "y". If an exception is raised during the iteration, it ' - 'is as if\n' - '"in" raised that exception.\n' - '\n' - 'Lastly, the old-style iteration protocol is tried: if a class ' - 'defines\n' - '"__getitem__()", "x in y" is "True" if and only if there is a ' - 'non-\n' - 'negative integer index *i* such that "x is y[i] or x == ' - 'y[i]", and no\n' - 'lower integer index raises the "IndexError" exception. (If ' - 'any other\n' - 'exception is raised, it is as if "in" raised that ' - 'exception).\n' - '\n' - 'The operator "not in" is defined to have the inverse truth ' - 'value of\n' - '"in".\n' - '\n' - '\n' - 'Identity comparisons\n' - '====================\n' - '\n' - 'The operators "is" and "is not" test for an object’s ' - 'identity: "x is\n' - 'y" is true if and only if *x* and *y* are the same object. ' - 'An\n' - 'Object’s identity is determined using the "id()" function. ' - '"x is not\n' - 'y" yields the inverse truth value. [4]\n', - 'compound': 'Compound statements\n' - '*******************\n' - '\n' - 'Compound statements contain (groups of) other statements; they ' - 'affect\n' - 'or control the execution of those other statements in some way. ' - 'In\n' - 'general, compound statements span multiple lines, although in ' - 'simple\n' - 'incarnations a whole compound statement may be contained in one ' - 'line.\n' - '\n' - 'The "if", "while" and "for" statements implement traditional ' - 'control\n' - 'flow constructs. "try" specifies exception handlers and/or ' - 'cleanup\n' - 'code for a group of statements, while the "with" statement ' - 'allows the\n' - 'execution of initialization and finalization code around a block ' - 'of\n' - 'code. Function and class definitions are also syntactically ' - 'compound\n' - 'statements.\n' - '\n' - 'A compound statement consists of one or more ‘clauses.’ A ' - 'clause\n' - 'consists of a header and a ‘suite.’ The clause headers of a\n' - 'particular compound statement are all at the same indentation ' - 'level.\n' - 'Each clause header begins with a uniquely identifying keyword ' - 'and ends\n' - 'with a colon. A suite is a group of statements controlled by a\n' - 'clause. A suite can be one or more semicolon-separated simple\n' - 'statements on the same line as the header, following the ' - 'header’s\n' - 'colon, or it can be one or more indented statements on ' - 'subsequent\n' - 'lines. Only the latter form of a suite can contain nested ' - 'compound\n' - 'statements; the following is illegal, mostly because it wouldn’t ' - 'be\n' - 'clear to which "if" clause a following "else" clause would ' - 'belong:\n' - '\n' - ' if test1: if test2: print(x)\n' - '\n' - 'Also note that the semicolon binds tighter than the colon in ' - 'this\n' - 'context, so that in the following example, either all or none of ' - 'the\n' - '"print()" calls are executed:\n' - '\n' - ' if x < y < z: print(x); print(y); print(z)\n' - '\n' - 'Summarizing:\n' - '\n' - ' compound_stmt ::= if_stmt\n' - ' | while_stmt\n' - ' | for_stmt\n' - ' | try_stmt\n' - ' | with_stmt\n' - ' | match_stmt\n' - ' | funcdef\n' - ' | classdef\n' - ' | async_with_stmt\n' - ' | async_for_stmt\n' - ' | async_funcdef\n' - ' suite ::= stmt_list NEWLINE | NEWLINE INDENT ' - 'statement+ DEDENT\n' - ' statement ::= stmt_list NEWLINE | compound_stmt\n' - ' stmt_list ::= simple_stmt (";" simple_stmt)* [";"]\n' - '\n' - 'Note that statements always end in a "NEWLINE" possibly followed ' - 'by a\n' - '"DEDENT". Also note that optional continuation clauses always ' - 'begin\n' - 'with a keyword that cannot start a statement, thus there are no\n' - 'ambiguities (the ‘dangling "else"’ problem is solved in Python ' - 'by\n' - 'requiring nested "if" statements to be indented).\n' - '\n' - 'The formatting of the grammar rules in the following sections ' - 'places\n' - 'each clause on a separate line for clarity.\n' - '\n' - '\n' - 'The "if" statement\n' - '==================\n' - '\n' - 'The "if" statement is used for conditional execution:\n' - '\n' - ' if_stmt ::= "if" assignment_expression ":" suite\n' - ' ("elif" assignment_expression ":" suite)*\n' - ' ["else" ":" suite]\n' - '\n' - 'It selects exactly one of the suites by evaluating the ' - 'expressions one\n' - 'by one until one is found to be true (see section Boolean ' - 'operations\n' - 'for the definition of true and false); then that suite is ' - 'executed\n' - '(and no other part of the "if" statement is executed or ' - 'evaluated).\n' - 'If all expressions are false, the suite of the "else" clause, ' - 'if\n' - 'present, is executed.\n' - '\n' - '\n' - 'The "while" statement\n' - '=====================\n' - '\n' - 'The "while" statement is used for repeated execution as long as ' - 'an\n' - 'expression is true:\n' - '\n' - ' while_stmt ::= "while" assignment_expression ":" suite\n' - ' ["else" ":" suite]\n' - '\n' - 'This repeatedly tests the expression and, if it is true, ' - 'executes the\n' - 'first suite; if the expression is false (which may be the first ' - 'time\n' - 'it is tested) the suite of the "else" clause, if present, is ' - 'executed\n' - 'and the loop terminates.\n' - '\n' - 'A "break" statement executed in the first suite terminates the ' - 'loop\n' - 'without executing the "else" clause’s suite. A "continue" ' - 'statement\n' - 'executed in the first suite skips the rest of the suite and goes ' - 'back\n' - 'to testing the expression.\n' - '\n' - '\n' - 'The "for" statement\n' - '===================\n' - '\n' - 'The "for" statement is used to iterate over the elements of a ' - 'sequence\n' - '(such as a string, tuple or list) or other iterable object:\n' - '\n' - ' for_stmt ::= "for" target_list "in" expression_list ":" ' - 'suite\n' - ' ["else" ":" suite]\n' - '\n' - 'The expression list is evaluated once; it should yield an ' - 'iterable\n' - 'object. An iterator is created for the result of the\n' - '"expression_list". The suite is then executed once for each ' - 'item\n' - 'provided by the iterator, in the order returned by the ' - 'iterator. Each\n' - 'item in turn is assigned to the target list using the standard ' - 'rules\n' - 'for assignments (see Assignment statements), and then the suite ' - 'is\n' - 'executed. When the items are exhausted (which is immediately ' - 'when the\n' - 'sequence is empty or an iterator raises a "StopIteration" ' - 'exception),\n' - 'the suite in the "else" clause, if present, is executed, and the ' - 'loop\n' - 'terminates.\n' - '\n' - 'A "break" statement executed in the first suite terminates the ' - 'loop\n' - 'without executing the "else" clause’s suite. A "continue" ' - 'statement\n' - 'executed in the first suite skips the rest of the suite and ' - 'continues\n' - 'with the next item, or with the "else" clause if there is no ' - 'next\n' - 'item.\n' - '\n' - 'The for-loop makes assignments to the variables in the target ' - 'list.\n' - 'This overwrites all previous assignments to those variables ' - 'including\n' - 'those made in the suite of the for-loop:\n' - '\n' - ' for i in range(10):\n' - ' print(i)\n' - ' i = 5 # this will not affect the for-loop\n' - ' # because i will be overwritten with ' - 'the next\n' - ' # index in the range\n' - '\n' - 'Names in the target list are not deleted when the loop is ' - 'finished,\n' - 'but if the sequence is empty, they will not have been assigned ' - 'to at\n' - 'all by the loop. Hint: the built-in function "range()" returns ' - 'an\n' - 'iterator of integers suitable to emulate the effect of Pascal’s ' - '"for i\n' - ':= a to b do"; e.g., "list(range(3))" returns the list "[0, 1, ' - '2]".\n' - '\n' - '\n' - 'The "try" statement\n' - '===================\n' - '\n' - 'The "try" statement specifies exception handlers and/or cleanup ' - 'code\n' - 'for a group of statements:\n' - '\n' - ' try_stmt ::= try1_stmt | try2_stmt\n' - ' try1_stmt ::= "try" ":" suite\n' - ' ("except" [expression ["as" identifier]] ":" ' - 'suite)+\n' - ' ["else" ":" suite]\n' - ' ["finally" ":" suite]\n' - ' try2_stmt ::= "try" ":" suite\n' - ' "finally" ":" suite\n' - '\n' - 'The "except" clause(s) specify one or more exception handlers. ' - 'When no\n' - 'exception occurs in the "try" clause, no exception handler is\n' - 'executed. When an exception occurs in the "try" suite, a search ' - 'for an\n' - 'exception handler is started. This search inspects the except ' - 'clauses\n' - 'in turn until one is found that matches the exception. An ' - 'expression-\n' - 'less except clause, if present, must be last; it matches any\n' - 'exception. For an except clause with an expression, that ' - 'expression\n' - 'is evaluated, and the clause matches the exception if the ' - 'resulting\n' - 'object is “compatible” with the exception. An object is ' - 'compatible\n' - 'with an exception if the object is the class or a *non-virtual ' - 'base\n' - 'class* of the exception object, or a tuple containing an item ' - 'that is\n' - 'the class or a non-virtual base class of the exception object.\n' - '\n' - 'If no except clause matches the exception, the search for an ' - 'exception\n' - 'handler continues in the surrounding code and on the invocation ' - 'stack.\n' - '[1]\n' - '\n' - 'If the evaluation of an expression in the header of an except ' - 'clause\n' - 'raises an exception, the original search for a handler is ' - 'canceled and\n' - 'a search starts for the new exception in the surrounding code ' - 'and on\n' - 'the call stack (it is treated as if the entire "try" statement ' - 'raised\n' - 'the exception).\n' - '\n' - 'When a matching except clause is found, the exception is ' - 'assigned to\n' - 'the target specified after the "as" keyword in that except ' - 'clause, if\n' - 'present, and the except clause’s suite is executed. All except\n' - 'clauses must have an executable block. When the end of this ' - 'block is\n' - 'reached, execution continues normally after the entire try ' - 'statement.\n' - '(This means that if two nested handlers exist for the same ' - 'exception,\n' - 'and the exception occurs in the try clause of the inner handler, ' - 'the\n' - 'outer handler will not handle the exception.)\n' - '\n' - 'When an exception has been assigned using "as target", it is ' - 'cleared\n' - 'at the end of the except clause. This is as if\n' - '\n' - ' except E as N:\n' - ' foo\n' - '\n' - 'was translated to\n' - '\n' - ' except E as N:\n' - ' try:\n' - ' foo\n' - ' finally:\n' - ' del N\n' - '\n' - 'This means the exception must be assigned to a different name to ' - 'be\n' - 'able to refer to it after the except clause. Exceptions are ' - 'cleared\n' - 'because with the traceback attached to them, they form a ' - 'reference\n' - 'cycle with the stack frame, keeping all locals in that frame ' - 'alive\n' - 'until the next garbage collection occurs.\n' - '\n' - 'Before an except clause’s suite is executed, details about the\n' - 'exception are stored in the "sys" module and can be accessed ' - 'via\n' - '"sys.exc_info()". "sys.exc_info()" returns a 3-tuple consisting ' - 'of the\n' - 'exception class, the exception instance and a traceback object ' - '(see\n' - 'section The standard type hierarchy) identifying the point in ' - 'the\n' - 'program where the exception occurred. The details about the ' - 'exception\n' - 'accessed via "sys.exc_info()" are restored to their previous ' - 'values\n' - 'when leaving an exception handler:\n' - '\n' - ' >>> print(sys.exc_info())\n' - ' (None, None, None)\n' - ' >>> try:\n' - ' ... raise TypeError\n' - ' ... except:\n' - ' ... print(sys.exc_info())\n' - ' ... try:\n' - ' ... raise ValueError\n' - ' ... except:\n' - ' ... print(sys.exc_info())\n' - ' ... print(sys.exc_info())\n' - ' ...\n' - " (<class 'TypeError'>, TypeError(), <traceback object at " - '0x10efad080>)\n' - " (<class 'ValueError'>, ValueError(), <traceback object at " - '0x10efad040>)\n' - " (<class 'TypeError'>, TypeError(), <traceback object at " - '0x10efad080>)\n' - ' >>> print(sys.exc_info())\n' - ' (None, None, None)\n' - '\n' - 'The optional "else" clause is executed if the control flow ' - 'leaves the\n' - '"try" suite, no exception was raised, and no "return", ' - '"continue", or\n' - '"break" statement was executed. Exceptions in the "else" clause ' - 'are\n' - 'not handled by the preceding "except" clauses.\n' - '\n' - 'If "finally" is present, it specifies a ‘cleanup’ handler. The ' - '"try"\n' - 'clause is executed, including any "except" and "else" clauses. ' - 'If an\n' - 'exception occurs in any of the clauses and is not handled, the\n' - 'exception is temporarily saved. The "finally" clause is ' - 'executed. If\n' - 'there is a saved exception it is re-raised at the end of the ' - '"finally"\n' - 'clause. If the "finally" clause raises another exception, the ' - 'saved\n' - 'exception is set as the context of the new exception. If the ' - '"finally"\n' - 'clause executes a "return", "break" or "continue" statement, the ' - 'saved\n' - 'exception is discarded:\n' - '\n' - ' >>> def f():\n' - ' ... try:\n' - ' ... 1/0\n' - ' ... finally:\n' - ' ... return 42\n' - ' ...\n' - ' >>> f()\n' - ' 42\n' - '\n' - 'The exception information is not available to the program ' - 'during\n' - 'execution of the "finally" clause.\n' - '\n' - 'When a "return", "break" or "continue" statement is executed in ' - 'the\n' - '"try" suite of a "try"…"finally" statement, the "finally" clause ' - 'is\n' - 'also executed ‘on the way out.’\n' - '\n' - 'The return value of a function is determined by the last ' - '"return"\n' - 'statement executed. Since the "finally" clause always executes, ' - 'a\n' - '"return" statement executed in the "finally" clause will always ' - 'be the\n' - 'last one executed:\n' - '\n' - ' >>> def foo():\n' - ' ... try:\n' - " ... return 'try'\n" - ' ... finally:\n' - " ... return 'finally'\n" - ' ...\n' - ' >>> foo()\n' - " 'finally'\n" - '\n' - 'Additional information on exceptions can be found in section\n' - 'Exceptions, and information on using the "raise" statement to ' - 'generate\n' - 'exceptions may be found in section The raise statement.\n' - '\n' - 'Changed in version 3.8: Prior to Python 3.8, a "continue" ' - 'statement\n' - 'was illegal in the "finally" clause due to a problem with the\n' - 'implementation.\n' - '\n' - '\n' - 'The "with" statement\n' - '====================\n' - '\n' - 'The "with" statement is used to wrap the execution of a block ' - 'with\n' - 'methods defined by a context manager (see section With ' - 'Statement\n' - 'Context Managers). This allows common "try"…"except"…"finally" ' - 'usage\n' - 'patterns to be encapsulated for convenient reuse.\n' - '\n' - ' with_stmt ::= "with" ( "(" with_stmt_contents ","? ' - '")" | with_stmt_contents ) ":" suite\n' - ' with_stmt_contents ::= with_item ("," with_item)*\n' - ' with_item ::= expression ["as" target]\n' - '\n' - 'The execution of the "with" statement with one “item” proceeds ' - 'as\n' - 'follows:\n' - '\n' - '1. The context expression (the expression given in the ' - '"with_item") is\n' - ' evaluated to obtain a context manager.\n' - '\n' - '2. The context manager’s "__enter__()" is loaded for later use.\n' - '\n' - '3. The context manager’s "__exit__()" is loaded for later use.\n' - '\n' - '4. The context manager’s "__enter__()" method is invoked.\n' - '\n' - '5. If a target was included in the "with" statement, the return ' - 'value\n' - ' from "__enter__()" is assigned to it.\n' - '\n' - ' Note:\n' - '\n' - ' The "with" statement guarantees that if the "__enter__()" ' - 'method\n' - ' returns without an error, then "__exit__()" will always be\n' - ' called. Thus, if an error occurs during the assignment to ' - 'the\n' - ' target list, it will be treated the same as an error ' - 'occurring\n' - ' within the suite would be. See step 6 below.\n' - '\n' - '6. The suite is executed.\n' - '\n' - '7. The context manager’s "__exit__()" method is invoked. If an\n' - ' exception caused the suite to be exited, its type, value, ' - 'and\n' - ' traceback are passed as arguments to "__exit__()". Otherwise, ' - 'three\n' - ' "None" arguments are supplied.\n' - '\n' - ' If the suite was exited due to an exception, and the return ' - 'value\n' - ' from the "__exit__()" method was false, the exception is ' - 'reraised.\n' - ' If the return value was true, the exception is suppressed, ' - 'and\n' - ' execution continues with the statement following the "with"\n' - ' statement.\n' - '\n' - ' If the suite was exited for any reason other than an ' - 'exception, the\n' - ' return value from "__exit__()" is ignored, and execution ' - 'proceeds\n' - ' at the normal location for the kind of exit that was taken.\n' - '\n' - 'The following code:\n' - '\n' - ' with EXPRESSION as TARGET:\n' - ' SUITE\n' - '\n' - 'is semantically equivalent to:\n' - '\n' - ' manager = (EXPRESSION)\n' - ' enter = type(manager).__enter__\n' - ' exit = type(manager).__exit__\n' - ' value = enter(manager)\n' - ' hit_except = False\n' - '\n' - ' try:\n' - ' TARGET = value\n' - ' SUITE\n' - ' except:\n' - ' hit_except = True\n' - ' if not exit(manager, *sys.exc_info()):\n' - ' raise\n' - ' finally:\n' - ' if not hit_except:\n' - ' exit(manager, None, None, None)\n' - '\n' - 'With more than one item, the context managers are processed as ' - 'if\n' - 'multiple "with" statements were nested:\n' - '\n' - ' with A() as a, B() as b:\n' - ' SUITE\n' - '\n' - 'is semantically equivalent to:\n' - '\n' - ' with A() as a:\n' - ' with B() as b:\n' - ' SUITE\n' - '\n' - 'You can also write multi-item context managers in multiple lines ' - 'if\n' - 'the items are surrounded by parentheses. For example:\n' - '\n' - ' with (\n' - ' A() as a,\n' - ' B() as b,\n' - ' ):\n' - ' SUITE\n' - '\n' - 'Changed in version 3.1: Support for multiple context ' - 'expressions.\n' - '\n' - 'Changed in version 3.10: Support for using grouping parentheses ' - 'to\n' - 'break the statement in multiple lines.\n' - '\n' - 'See also:\n' - '\n' - ' **PEP 343** - The “with” statement\n' - ' The specification, background, and examples for the Python ' - '"with"\n' - ' statement.\n' - '\n' - '\n' - 'The "match" statement\n' - '=====================\n' - '\n' - 'New in version 3.10.\n' - '\n' - 'The match statement is used for pattern matching. Syntax:\n' - '\n' - ' match_stmt ::= \'match\' subject_expr ":" NEWLINE INDENT ' - 'case_block+ DEDENT\n' - ' subject_expr ::= star_named_expression "," ' - 'star_named_expressions?\n' - ' | named_expression\n' - ' case_block ::= \'case\' patterns [guard] ":" block\n' - '\n' - 'Note:\n' - '\n' - ' This section uses single quotes to denote soft keywords.\n' - '\n' - 'Pattern matching takes a pattern as input (following "case") and ' - 'a\n' - 'subject value (following "match"). The pattern (which may ' - 'contain\n' - 'subpatterns) is matched against the subject value. The outcomes ' - 'are:\n' - '\n' - '* A match success or failure (also termed a pattern success or\n' - ' failure).\n' - '\n' - '* Possible binding of matched values to a name. The ' - 'prerequisites for\n' - ' this are further discussed below.\n' - '\n' - 'The "match" and "case" keywords are soft keywords.\n' - '\n' - 'See also:\n' - '\n' - ' * **PEP 634** – Structural Pattern Matching: Specification\n' - '\n' - ' * **PEP 636** – Structural Pattern Matching: Tutorial\n' - '\n' - '\n' - 'Overview\n' - '--------\n' - '\n' - 'Here’s an overview of the logical flow of a match statement:\n' - '\n' - '1. The subject expression "subject_expr" is evaluated and a ' - 'resulting\n' - ' subject value obtained. If the subject expression contains a ' - 'comma,\n' - ' a tuple is constructed using the standard rules.\n' - '\n' - '2. Each pattern in a "case_block" is attempted to match with ' - 'the\n' - ' subject value. The specific rules for success or failure are\n' - ' described below. The match attempt can also bind some or all ' - 'of the\n' - ' standalone names within the pattern. The precise pattern ' - 'binding\n' - ' rules vary per pattern type and are specified below. **Name\n' - ' bindings made during a successful pattern match outlive the\n' - ' executed block and can be used after the match statement**.\n' - '\n' - ' Note:\n' - '\n' - ' During failed pattern matches, some subpatterns may ' - 'succeed.\n' - ' Do not rely on bindings being made for a failed match.\n' - ' Conversely, do not rely on variables remaining unchanged ' - 'after\n' - ' a failed match. The exact behavior is dependent on\n' - ' implementation and may vary. This is an intentional ' - 'decision\n' - ' made to allow different implementations to add ' - 'optimizations.\n' - '\n' - '3. If the pattern succeeds, the corresponding guard (if present) ' - 'is\n' - ' evaluated. In this case all name bindings are guaranteed to ' - 'have\n' - ' happened.\n' - '\n' - ' * If the guard evaluates as true or is missing, the "block" ' - 'inside\n' - ' "case_block" is executed.\n' - '\n' - ' * Otherwise, the next "case_block" is attempted as described ' - 'above.\n' - '\n' - ' * If there are no further case blocks, the match statement ' - 'is\n' - ' completed.\n' - '\n' - 'Note:\n' - '\n' - ' Users should generally never rely on a pattern being ' - 'evaluated.\n' - ' Depending on implementation, the interpreter may cache values ' - 'or use\n' - ' other optimizations which skip repeated evaluations.\n' - '\n' - 'A sample match statement:\n' - '\n' - ' >>> flag = False\n' - ' >>> match (100, 200):\n' - ' ... case (100, 300): # Mismatch: 200 != 300\n' - " ... print('Case 1')\n" - ' ... case (100, 200) if flag: # Successful match, but ' - 'guard fails\n' - " ... print('Case 2')\n" - ' ... case (100, y): # Matches and binds y to 200\n' - " ... print(f'Case 3, y: {y}')\n" - ' ... case _: # Pattern not attempted\n' - " ... print('Case 4, I match anything!')\n" - ' ...\n' - ' Case 3, y: 200\n' - '\n' - 'In this case, "if flag" is a guard. Read more about that in the ' - 'next\n' - 'section.\n' - '\n' - '\n' - 'Guards\n' - '------\n' - '\n' - ' guard ::= "if" named_expression\n' - '\n' - 'A "guard" (which is part of the "case") must succeed for code ' - 'inside\n' - 'the "case" block to execute. It takes the form: "if" followed ' - 'by an\n' - 'expression.\n' - '\n' - 'The logical flow of a "case" block with a "guard" follows:\n' - '\n' - '1. Check that the pattern in the "case" block succeeded. If ' - 'the\n' - ' pattern failed, the "guard" is not evaluated and the next ' - '"case"\n' - ' block is checked.\n' - '\n' - '2. If the pattern succeeded, evaluate the "guard".\n' - '\n' - ' * If the "guard" condition evaluates as true, the case block ' - 'is\n' - ' selected.\n' - '\n' - ' * If the "guard" condition evaluates as false, the case block ' - 'is\n' - ' not selected.\n' - '\n' - ' * If the "guard" raises an exception during evaluation, the\n' - ' exception bubbles up.\n' - '\n' - 'Guards are allowed to have side effects as they are ' - 'expressions.\n' - 'Guard evaluation must proceed from the first to the last case ' - 'block,\n' - 'one at a time, skipping case blocks whose pattern(s) don’t all\n' - 'succeed. (I.e., guard evaluation must happen in order.) Guard\n' - 'evaluation must stop once a case block is selected.\n' - '\n' - '\n' - 'Irrefutable Case Blocks\n' - '-----------------------\n' - '\n' - 'An irrefutable case block is a match-all case block. A match\n' - 'statement may have at most one irrefutable case block, and it ' - 'must be\n' - 'last.\n' - '\n' - 'A case block is considered irrefutable if it has no guard and ' - 'its\n' - 'pattern is irrefutable. A pattern is considered irrefutable if ' - 'we can\n' - 'prove from its syntax alone that it will always succeed. Only ' - 'the\n' - 'following patterns are irrefutable:\n' - '\n' - '* AS Patterns whose left-hand side is irrefutable\n' - '\n' - '* OR Patterns containing at least one irrefutable pattern\n' - '\n' - '* Capture Patterns\n' - '\n' - '* Wildcard Patterns\n' - '\n' - '* parenthesized irrefutable patterns\n' - '\n' - '\n' - 'Patterns\n' - '--------\n' - '\n' - 'Note:\n' - '\n' - ' This section uses grammar notations beyond standard EBNF:\n' - '\n' - ' * the notation "SEP.RULE+" is shorthand for "RULE (SEP ' - 'RULE)*"\n' - '\n' - ' * the notation "!RULE" is shorthand for a negative lookahead\n' - ' assertion\n' - '\n' - 'The top-level syntax for "patterns" is:\n' - '\n' - ' patterns ::= open_sequence_pattern | pattern\n' - ' pattern ::= as_pattern | or_pattern\n' - ' closed_pattern ::= | literal_pattern\n' - ' | capture_pattern\n' - ' | wildcard_pattern\n' - ' | value_pattern\n' - ' | group_pattern\n' - ' | sequence_pattern\n' - ' | mapping_pattern\n' - ' | class_pattern\n' - '\n' - 'The descriptions below will include a description “in simple ' - 'terms” of\n' - 'what a pattern does for illustration purposes (credits to ' - 'Raymond\n' - 'Hettinger for a document that inspired most of the ' - 'descriptions). Note\n' - 'that these descriptions are purely for illustration purposes and ' - '**may\n' - 'not** reflect the underlying implementation. Furthermore, they ' - 'do not\n' - 'cover all valid forms.\n' - '\n' - '\n' - 'OR Patterns\n' - '~~~~~~~~~~~\n' - '\n' - 'An OR pattern is two or more patterns separated by vertical bars ' - '"|".\n' - 'Syntax:\n' - '\n' - ' or_pattern ::= "|".closed_pattern+\n' - '\n' - 'Only the final subpattern may be irrefutable, and each ' - 'subpattern must\n' - 'bind the same set of names to avoid ambiguity.\n' - '\n' - 'An OR pattern matches each of its subpatterns in turn to the ' - 'subject\n' - 'value, until one succeeds. The OR pattern is then considered\n' - 'successful. Otherwise, if none of the subpatterns succeed, the ' - 'OR\n' - 'pattern fails.\n' - '\n' - 'In simple terms, "P1 | P2 | ..." will try to match "P1", if it ' - 'fails\n' - 'it will try to match "P2", succeeding immediately if any ' - 'succeeds,\n' - 'failing otherwise.\n' - '\n' - '\n' - 'AS Patterns\n' - '~~~~~~~~~~~\n' - '\n' - 'An AS pattern matches an OR pattern on the left of the "as" ' - 'keyword\n' - 'against a subject. Syntax:\n' - '\n' - ' as_pattern ::= or_pattern "as" capture_pattern\n' - '\n' - 'If the OR pattern fails, the AS pattern fails. Otherwise, the ' - 'AS\n' - 'pattern binds the subject to the name on the right of the as ' - 'keyword\n' - 'and succeeds. "capture_pattern" cannot be a a "_".\n' - '\n' - 'In simple terms "P as NAME" will match with "P", and on success ' - 'it\n' - 'will set "NAME = <subject>".\n' - '\n' - '\n' - 'Literal Patterns\n' - '~~~~~~~~~~~~~~~~\n' - '\n' - 'A literal pattern corresponds to most literals in Python. ' - 'Syntax:\n' - '\n' - ' literal_pattern ::= signed_number\n' - ' | signed_number "+" NUMBER\n' - ' | signed_number "-" NUMBER\n' - ' | strings\n' - ' | "None"\n' - ' | "True"\n' - ' | "False"\n' - ' | signed_number: NUMBER | "-" NUMBER\n' - '\n' - 'The rule "strings" and the token "NUMBER" are defined in the ' - 'standard\n' - 'Python grammar. Triple-quoted strings are supported. Raw ' - 'strings and\n' - 'byte strings are supported. Formatted string literals are not\n' - 'supported.\n' - '\n' - 'The forms "signed_number \'+\' NUMBER" and "signed_number \'-\' ' - 'NUMBER"\n' - 'are for expressing complex numbers; they require a real number ' - 'on the\n' - 'left and an imaginary number on the right. E.g. "3 + 4j".\n' - '\n' - 'In simple terms, "LITERAL" will succeed only if "<subject> ==\n' - 'LITERAL". For the singletons "None", "True" and "False", the ' - '"is"\n' - 'operator is used.\n' - '\n' - '\n' - 'Capture Patterns\n' - '~~~~~~~~~~~~~~~~\n' - '\n' - 'A capture pattern binds the subject value to a name. Syntax:\n' - '\n' - " capture_pattern ::= !'_' NAME\n" - '\n' - 'A single underscore "_" is not a capture pattern (this is what ' - '"!\'_\'"\n' - 'expresses). It is instead treated as a "wildcard_pattern".\n' - '\n' - 'In a given pattern, a given name can only be bound once. E.g. ' - '"case\n' - 'x, x: ..." is invalid while "case [x] | x: ..." is allowed.\n' - '\n' - 'Capture patterns always succeed. The binding follows scoping ' - 'rules\n' - 'established by the assignment expression operator in **PEP ' - '572**; the\n' - 'name becomes a local variable in the closest containing function ' - 'scope\n' - 'unless there’s an applicable "global" or "nonlocal" statement.\n' - '\n' - 'In simple terms "NAME" will always succeed and it will set "NAME ' - '=\n' - '<subject>".\n' - '\n' - '\n' - 'Wildcard Patterns\n' - '~~~~~~~~~~~~~~~~~\n' - '\n' - 'A wildcard pattern always succeeds (matches anything) and binds ' - 'no\n' - 'name. Syntax:\n' - '\n' - " wildcard_pattern ::= '_'\n" - '\n' - '"_" is a soft keyword within any pattern, but only within ' - 'patterns.\n' - 'It is an identifier, as usual, even within "match" subject\n' - 'expressions, "guard"s, and "case" blocks.\n' - '\n' - 'In simple terms, "_" will always succeed.\n' - '\n' - '\n' - 'Value Patterns\n' - '~~~~~~~~~~~~~~\n' - '\n' - 'A value pattern represents a named value in Python. Syntax:\n' - '\n' - ' value_pattern ::= attr\n' - ' attr ::= name_or_attr "." NAME\n' - ' name_or_attr ::= attr | NAME\n' - '\n' - 'The dotted name in the pattern is looked up using standard ' - 'Python name\n' - 'resolution rules. The pattern succeeds if the value found ' - 'compares\n' - 'equal to the subject value (using the "==" equality operator).\n' - '\n' - 'In simple terms "NAME1.NAME2" will succeed only if "<subject> ' - '==\n' - 'NAME1.NAME2"\n' - '\n' - 'Note:\n' - '\n' - ' If the same value occurs multiple times in the same match ' - 'statement,\n' - ' the interpreter may cache the first value found and reuse it ' - 'rather\n' - ' than repeat the same lookup. This cache is strictly tied to a ' - 'given\n' - ' execution of a given match statement.\n' - '\n' - '\n' - 'Group Patterns\n' - '~~~~~~~~~~~~~~\n' - '\n' - 'A group pattern allows users to add parentheses around patterns ' - 'to\n' - 'emphasize the intended grouping. Otherwise, it has no ' - 'additional\n' - 'syntax. Syntax:\n' - '\n' - ' group_pattern ::= "(" pattern ")"\n' - '\n' - 'In simple terms "(P)" has the same effect as "P".\n' - '\n' - '\n' - 'Sequence Patterns\n' - '~~~~~~~~~~~~~~~~~\n' - '\n' - 'A sequence pattern contains several subpatterns to be matched ' - 'against\n' - 'sequence elements. The syntax is similar to the unpacking of a ' - 'list or\n' - 'tuple.\n' - '\n' - ' sequence_pattern ::= "[" [maybe_sequence_pattern] "]"\n' - ' | "(" [open_sequence_pattern] ")"\n' - ' open_sequence_pattern ::= maybe_star_pattern "," ' - '[maybe_sequence_pattern]\n' - ' maybe_sequence_pattern ::= ",".maybe_star_pattern+ ","?\n' - ' maybe_star_pattern ::= star_pattern | pattern\n' - ' star_pattern ::= "*" (capture_pattern | ' - 'wildcard_pattern)\n' - '\n' - 'There is no difference if parentheses or square brackets are ' - 'used for\n' - 'sequence patterns (i.e. "(...)" vs "[...]" ).\n' - '\n' - 'Note:\n' - '\n' - ' A single pattern enclosed in parentheses without a trailing ' - 'comma\n' - ' (e.g. "(3 | 4)") is a group pattern. While a single pattern ' - 'enclosed\n' - ' in square brackets (e.g. "[3 | 4]") is still a sequence ' - 'pattern.\n' - '\n' - 'At most one star subpattern may be in a sequence pattern. The ' - 'star\n' - 'subpattern may occur in any position. If no star subpattern is\n' - 'present, the sequence pattern is a fixed-length sequence ' - 'pattern;\n' - 'otherwise it is a variable-length sequence pattern.\n' - '\n' - 'The following is the logical flow for matching a sequence ' - 'pattern\n' - 'against a subject value:\n' - '\n' - '1. If the subject value is not a sequence [2], the sequence ' - 'pattern\n' - ' fails.\n' - '\n' - '2. If the subject value is an instance of "str", "bytes" or\n' - ' "bytearray" the sequence pattern fails.\n' - '\n' - '3. The subsequent steps depend on whether the sequence pattern ' - 'is\n' - ' fixed or variable-length.\n' - '\n' - ' If the sequence pattern is fixed-length:\n' - '\n' - ' 1. If the length of the subject sequence is not equal to the ' - 'number\n' - ' of subpatterns, the sequence pattern fails\n' - '\n' - ' 2. Subpatterns in the sequence pattern are matched to their\n' - ' corresponding items in the subject sequence from left to ' - 'right.\n' - ' Matching stops as soon as a subpattern fails. If all\n' - ' subpatterns succeed in matching their corresponding item, ' - 'the\n' - ' sequence pattern succeeds.\n' - '\n' - ' Otherwise, if the sequence pattern is variable-length:\n' - '\n' - ' 1. If the length of the subject sequence is less than the ' - 'number of\n' - ' non-star subpatterns, the sequence pattern fails.\n' - '\n' - ' 2. The leading non-star subpatterns are matched to their\n' - ' corresponding items as for fixed-length sequences.\n' - '\n' - ' 3. If the previous step succeeds, the star subpattern matches ' - 'a\n' - ' list formed of the remaining subject items, excluding the\n' - ' remaining items corresponding to non-star subpatterns ' - 'following\n' - ' the star subpattern.\n' - '\n' - ' 4. Remaining non-star subpatterns are matched to their\n' - ' corresponding subject items, as for a fixed-length ' - 'sequence.\n' - '\n' - ' Note:\n' - '\n' - ' The length of the subject sequence is obtained via "len()" ' - '(i.e.\n' - ' via the "__len__()" protocol). This length may be cached ' - 'by the\n' - ' interpreter in a similar manner as value patterns.\n' - '\n' - 'In simple terms "[P1, P2, P3," … ", P<N>]" matches only if all ' - 'the\n' - 'following happens:\n' - '\n' - '* check "<subject>" is a sequence\n' - '\n' - '* "len(subject) == <N>"\n' - '\n' - '* "P1" matches "<subject>[0]" (note that this match can also ' - 'bind\n' - ' names)\n' - '\n' - '* "P2" matches "<subject>[1]" (note that this match can also ' - 'bind\n' - ' names)\n' - '\n' - '* … and so on for the corresponding pattern/element.\n' - '\n' - '\n' - 'Mapping Patterns\n' - '~~~~~~~~~~~~~~~~\n' - '\n' - 'A mapping pattern contains one or more key-value patterns. The ' - 'syntax\n' - 'is similar to the construction of a dictionary. Syntax:\n' - '\n' - ' mapping_pattern ::= "{" [items_pattern] "}"\n' - ' items_pattern ::= ",".key_value_pattern+ ","?\n' - ' key_value_pattern ::= (literal_pattern | value_pattern) ":" ' - 'pattern\n' - ' | double_star_pattern\n' - ' double_star_pattern ::= "**" capture_pattern\n' - '\n' - 'At most one double star pattern may be in a mapping pattern. ' - 'The\n' - 'double star pattern must be the last subpattern in the mapping\n' - 'pattern.\n' - '\n' - 'Duplicate keys in mapping patterns are disallowed. Duplicate ' - 'literal\n' - 'keys will raise a "SyntaxError". Two keys that otherwise have ' - 'the same\n' - 'value will raise a "ValueError" at runtime.\n' - '\n' - 'The following is the logical flow for matching a mapping ' - 'pattern\n' - 'against a subject value:\n' - '\n' - '1. If the subject value is not a mapping [3],the mapping ' - 'pattern\n' - ' fails.\n' - '\n' - '2. If every key given in the mapping pattern is present in the ' - 'subject\n' - ' mapping, and the pattern for each key matches the ' - 'corresponding\n' - ' item of the subject mapping, the mapping pattern succeeds.\n' - '\n' - '3. If duplicate keys are detected in the mapping pattern, the ' - 'pattern\n' - ' is considered invalid. A "SyntaxError" is raised for ' - 'duplicate\n' - ' literal values; or a "ValueError" for named keys of the same ' - 'value.\n' - '\n' - 'Note:\n' - '\n' - ' Key-value pairs are matched using the two-argument form of ' - 'the\n' - ' mapping subject’s "get()" method. Matched key-value pairs ' - 'must\n' - ' already be present in the mapping, and not created on-the-fly ' - 'via\n' - ' "__missing__()" or "__getitem__()".\n' - '\n' - 'In simple terms "{KEY1: P1, KEY2: P2, ... }" matches only if all ' - 'the\n' - 'following happens:\n' - '\n' - '* check "<subject>" is a mapping\n' - '\n' - '* "KEY1 in <subject>"\n' - '\n' - '* "P1" matches "<subject>[KEY1]"\n' - '\n' - '* … and so on for the corresponding KEY/pattern pair.\n' - '\n' - '\n' - 'Class Patterns\n' - '~~~~~~~~~~~~~~\n' - '\n' - 'A class pattern represents a class and its positional and ' - 'keyword\n' - 'arguments (if any). Syntax:\n' - '\n' - ' class_pattern ::= name_or_attr "(" [pattern_arguments ' - '","?] ")"\n' - ' pattern_arguments ::= positional_patterns ["," ' - 'keyword_patterns]\n' - ' | keyword_patterns\n' - ' positional_patterns ::= ",".pattern+\n' - ' keyword_patterns ::= ",".keyword_pattern+\n' - ' keyword_pattern ::= NAME "=" pattern\n' - '\n' - 'The same keyword should not be repeated in class patterns.\n' - '\n' - 'The following is the logical flow for matching a class pattern ' - 'against\n' - 'a subject value:\n' - '\n' - '1. If "name_or_attr" is not an instance of the builtin "type" , ' - 'raise\n' - ' "TypeError".\n' - '\n' - '2. If the subject value is not an instance of "name_or_attr" ' - '(tested\n' - ' via "isinstance()"), the class pattern fails.\n' - '\n' - '3. If no pattern arguments are present, the pattern succeeds.\n' - ' Otherwise, the subsequent steps depend on whether keyword or\n' - ' positional argument patterns are present.\n' - '\n' - ' For a number of built-in types (specified below), a single\n' - ' positional subpattern is accepted which will match the ' - 'entire\n' - ' subject; for these types keyword patterns also work as for ' - 'other\n' - ' types.\n' - '\n' - ' If only keyword patterns are present, they are processed as\n' - ' follows, one by one:\n' - '\n' - ' I. The keyword is looked up as an attribute on the subject.\n' - '\n' - ' * If this raises an exception other than "AttributeError", ' - 'the\n' - ' exception bubbles up.\n' - '\n' - ' * If this raises "AttributeError", the class pattern has ' - 'failed.\n' - '\n' - ' * Else, the subpattern associated with the keyword pattern ' - 'is\n' - ' matched against the subject’s attribute value. If this ' - 'fails,\n' - ' the class pattern fails; if this succeeds, the match ' - 'proceeds\n' - ' to the next keyword.\n' - '\n' - ' II. If all keyword patterns succeed, the class pattern ' - 'succeeds.\n' - '\n' - ' If any positional patterns are present, they are converted ' - 'to\n' - ' keyword patterns using the "__match_args__" attribute on the ' - 'class\n' - ' "name_or_attr" before matching:\n' - '\n' - ' I. The equivalent of "getattr(cls, "__match_args__", ())" is\n' - ' called.\n' - '\n' - ' * If this raises an exception, the exception bubbles up.\n' - '\n' - ' * If the returned value is not a tuple, the conversion ' - 'fails and\n' - ' "TypeError" is raised.\n' - '\n' - ' * If there are more positional patterns than\n' - ' "len(cls.__match_args__)", "TypeError" is raised.\n' - '\n' - ' * Otherwise, positional pattern "i" is converted to a ' - 'keyword\n' - ' pattern using "__match_args__[i]" as the keyword.\n' - ' "__match_args__[i]" must be a string; if not "TypeError" ' - 'is\n' - ' raised.\n' - '\n' - ' * If there are duplicate keywords, "TypeError" is raised.\n' - '\n' - ' See also:\n' - '\n' - ' Customizing positional arguments in class pattern ' - 'matching\n' - '\n' - ' II. Once all positional patterns have been converted to ' - 'keyword\n' - ' patterns,\n' - ' the match proceeds as if there were only keyword ' - 'patterns.\n' - '\n' - ' For the following built-in types the handling of positional\n' - ' subpatterns is different:\n' - '\n' - ' * "bool"\n' - '\n' - ' * "bytearray"\n' - '\n' - ' * "bytes"\n' - '\n' - ' * "dict"\n' - '\n' - ' * "float"\n' - '\n' - ' * "frozenset"\n' - '\n' - ' * "int"\n' - '\n' - ' * "list"\n' - '\n' - ' * "set"\n' - '\n' - ' * "str"\n' - '\n' - ' * "tuple"\n' - '\n' - ' These classes accept a single positional argument, and the ' - 'pattern\n' - ' there is matched against the whole object rather than an ' - 'attribute.\n' - ' For example "int(0|1)" matches the value "0", but not the ' - 'values\n' - ' "0.0" or "False".\n' - '\n' - 'In simple terms "CLS(P1, attr=P2)" matches only if the ' - 'following\n' - 'happens:\n' - '\n' - '* "isinstance(<subject>, CLS)"\n' - '\n' - '* convert "P1" to a keyword pattern using "CLS.__match_args__"\n' - '\n' - '* For each keyword argument "attr=P2":\n' - ' * "hasattr(<subject>, "attr")"\n' - '\n' - ' * "P2" matches "<subject>.attr"\n' - '\n' - '* … and so on for the corresponding keyword argument/pattern ' - 'pair.\n' - '\n' - 'See also:\n' - '\n' - ' * **PEP 634** – Structural Pattern Matching: Specification\n' - '\n' - ' * **PEP 636** – Structural Pattern Matching: Tutorial\n' - '\n' - '\n' - 'Function definitions\n' - '====================\n' - '\n' - 'A function definition defines a user-defined function object ' - '(see\n' - 'section The standard type hierarchy):\n' - '\n' - ' funcdef ::= [decorators] "def" funcname "(" ' - '[parameter_list] ")"\n' - ' ["->" expression] ":" suite\n' - ' decorators ::= decorator+\n' - ' decorator ::= "@" assignment_expression ' - 'NEWLINE\n' - ' parameter_list ::= defparameter ("," ' - 'defparameter)* "," "/" ["," [parameter_list_no_posonly]]\n' - ' | parameter_list_no_posonly\n' - ' parameter_list_no_posonly ::= defparameter ("," ' - 'defparameter)* ["," [parameter_list_starargs]]\n' - ' | parameter_list_starargs\n' - ' parameter_list_starargs ::= "*" [parameter] ("," ' - 'defparameter)* ["," ["**" parameter [","]]]\n' - ' | "**" parameter [","]\n' - ' parameter ::= identifier [":" expression]\n' - ' defparameter ::= parameter ["=" expression]\n' - ' funcname ::= identifier\n' - '\n' - 'A function definition is an executable statement. Its execution ' - 'binds\n' - 'the function name in the current local namespace to a function ' - 'object\n' - '(a wrapper around the executable code for the function). This\n' - 'function object contains a reference to the current global ' - 'namespace\n' - 'as the global namespace to be used when the function is called.\n' - '\n' - 'The function definition does not execute the function body; this ' - 'gets\n' - 'executed only when the function is called. [4]\n' - '\n' - 'A function definition may be wrapped by one or more *decorator*\n' - 'expressions. Decorator expressions are evaluated when the ' - 'function is\n' - 'defined, in the scope that contains the function definition. ' - 'The\n' - 'result must be a callable, which is invoked with the function ' - 'object\n' - 'as the only argument. The returned value is bound to the ' - 'function name\n' - 'instead of the function object. Multiple decorators are applied ' - 'in\n' - 'nested fashion. For example, the following code\n' - '\n' - ' @f1(arg)\n' - ' @f2\n' - ' def func(): pass\n' - '\n' - 'is roughly equivalent to\n' - '\n' - ' def func(): pass\n' - ' func = f1(arg)(f2(func))\n' - '\n' - 'except that the original function is not temporarily bound to ' - 'the name\n' - '"func".\n' - '\n' - 'Changed in version 3.9: Functions may be decorated with any ' - 'valid\n' - '"assignment_expression". Previously, the grammar was much more\n' - 'restrictive; see **PEP 614** for details.\n' - '\n' - 'When one or more *parameters* have the form *parameter* "="\n' - '*expression*, the function is said to have “default parameter ' - 'values.”\n' - 'For a parameter with a default value, the corresponding ' - '*argument* may\n' - 'be omitted from a call, in which case the parameter’s default ' - 'value is\n' - 'substituted. If a parameter has a default value, all following\n' - 'parameters up until the “"*"” must also have a default value — ' - 'this is\n' - 'a syntactic restriction that is not expressed by the grammar.\n' - '\n' - '**Default parameter values are evaluated from left to right when ' - 'the\n' - 'function definition is executed.** This means that the ' - 'expression is\n' - 'evaluated once, when the function is defined, and that the same ' - '“pre-\n' - 'computed” value is used for each call. This is especially ' - 'important\n' - 'to understand when a default parameter value is a mutable ' - 'object, such\n' - 'as a list or a dictionary: if the function modifies the object ' - '(e.g.\n' - 'by appending an item to a list), the default parameter value is ' - 'in\n' - 'effect modified. This is generally not what was intended. A ' - 'way\n' - 'around this is to use "None" as the default, and explicitly test ' - 'for\n' - 'it in the body of the function, e.g.:\n' - '\n' - ' def whats_on_the_telly(penguin=None):\n' - ' if penguin is None:\n' - ' penguin = []\n' - ' penguin.append("property of the zoo")\n' - ' return penguin\n' - '\n' - 'Function call semantics are described in more detail in section ' - 'Calls.\n' - 'A function call always assigns values to all parameters ' - 'mentioned in\n' - 'the parameter list, either from positional arguments, from ' - 'keyword\n' - 'arguments, or from default values. If the form “"*identifier"” ' - 'is\n' - 'present, it is initialized to a tuple receiving any excess ' - 'positional\n' - 'parameters, defaulting to the empty tuple. If the form\n' - '“"**identifier"” is present, it is initialized to a new ordered\n' - 'mapping receiving any excess keyword arguments, defaulting to a ' - 'new\n' - 'empty mapping of the same type. Parameters after “"*"” or\n' - '“"*identifier"” are keyword-only parameters and may only be ' - 'passed by\n' - 'keyword arguments. Parameters before “"/"” are positional-only\n' - 'parameters and may only be passed by positional arguments.\n' - '\n' - 'Changed in version 3.8: The "/" function parameter syntax may be ' - 'used\n' - 'to indicate positional-only parameters. See **PEP 570** for ' - 'details.\n' - '\n' - 'Parameters may have an *annotation* of the form “": ' - 'expression"”\n' - 'following the parameter name. Any parameter may have an ' - 'annotation,\n' - 'even those of the form "*identifier" or "**identifier". ' - 'Functions may\n' - 'have “return” annotation of the form “"-> expression"” after ' - 'the\n' - 'parameter list. These annotations can be any valid Python ' - 'expression.\n' - 'The presence of annotations does not change the semantics of a\n' - 'function. The annotation values are available as values of a\n' - 'dictionary keyed by the parameters’ names in the ' - '"__annotations__"\n' - 'attribute of the function object. If the "annotations" import ' - 'from\n' - '"__future__" is used, annotations are preserved as strings at ' - 'runtime\n' - 'which enables postponed evaluation. Otherwise, they are ' - 'evaluated\n' - 'when the function definition is executed. In this case ' - 'annotations\n' - 'may be evaluated in a different order than they appear in the ' - 'source\n' - 'code.\n' - '\n' - 'It is also possible to create anonymous functions (functions not ' - 'bound\n' - 'to a name), for immediate use in expressions. This uses lambda\n' - 'expressions, described in section Lambdas. Note that the ' - 'lambda\n' - 'expression is merely a shorthand for a simplified function ' - 'definition;\n' - 'a function defined in a “"def"” statement can be passed around ' - 'or\n' - 'assigned to another name just like a function defined by a ' - 'lambda\n' - 'expression. The “"def"” form is actually more powerful since ' - 'it\n' - 'allows the execution of multiple statements and annotations.\n' - '\n' - '**Programmer’s note:** Functions are first-class objects. A ' - '“"def"”\n' - 'statement executed inside a function definition defines a local\n' - 'function that can be returned or passed around. Free variables ' - 'used\n' - 'in the nested function can access the local variables of the ' - 'function\n' - 'containing the def. See section Naming and binding for ' - 'details.\n' - '\n' - 'See also:\n' - '\n' - ' **PEP 3107** - Function Annotations\n' - ' The original specification for function annotations.\n' - '\n' - ' **PEP 484** - Type Hints\n' - ' Definition of a standard meaning for annotations: type ' - 'hints.\n' - '\n' - ' **PEP 526** - Syntax for Variable Annotations\n' - ' Ability to type hint variable declarations, including ' - 'class\n' - ' variables and instance variables\n' - '\n' - ' **PEP 563** - Postponed Evaluation of Annotations\n' - ' Support for forward references within annotations by ' - 'preserving\n' - ' annotations in a string form at runtime instead of eager\n' - ' evaluation.\n' - '\n' - '\n' - 'Class definitions\n' - '=================\n' - '\n' - 'A class definition defines a class object (see section The ' - 'standard\n' - 'type hierarchy):\n' - '\n' - ' classdef ::= [decorators] "class" classname [inheritance] ' - '":" suite\n' - ' inheritance ::= "(" [argument_list] ")"\n' - ' classname ::= identifier\n' - '\n' - 'A class definition is an executable statement. The inheritance ' - 'list\n' - 'usually gives a list of base classes (see Metaclasses for more\n' - 'advanced uses), so each item in the list should evaluate to a ' - 'class\n' - 'object which allows subclassing. Classes without an inheritance ' - 'list\n' - 'inherit, by default, from the base class "object"; hence,\n' - '\n' - ' class Foo:\n' - ' pass\n' - '\n' - 'is equivalent to\n' - '\n' - ' class Foo(object):\n' - ' pass\n' - '\n' - 'The class’s suite is then executed in a new execution frame ' - '(see\n' - 'Naming and binding), using a newly created local namespace and ' - 'the\n' - 'original global namespace. (Usually, the suite contains mostly\n' - 'function definitions.) When the class’s suite finishes ' - 'execution, its\n' - 'execution frame is discarded but its local namespace is saved. ' - '[5] A\n' - 'class object is then created using the inheritance list for the ' - 'base\n' - 'classes and the saved local namespace for the attribute ' - 'dictionary.\n' - 'The class name is bound to this class object in the original ' - 'local\n' - 'namespace.\n' - '\n' - 'The order in which attributes are defined in the class body is\n' - 'preserved in the new class’s "__dict__". Note that this is ' - 'reliable\n' - 'only right after the class is created and only for classes that ' - 'were\n' - 'defined using the definition syntax.\n' - '\n' - 'Class creation can be customized heavily using metaclasses.\n' - '\n' - 'Classes can also be decorated: just like when decorating ' - 'functions,\n' - '\n' - ' @f1(arg)\n' - ' @f2\n' - ' class Foo: pass\n' - '\n' - 'is roughly equivalent to\n' - '\n' - ' class Foo: pass\n' - ' Foo = f1(arg)(f2(Foo))\n' - '\n' - 'The evaluation rules for the decorator expressions are the same ' - 'as for\n' - 'function decorators. The result is then bound to the class ' - 'name.\n' - '\n' - 'Changed in version 3.9: Classes may be decorated with any valid\n' - '"assignment_expression". Previously, the grammar was much more\n' - 'restrictive; see **PEP 614** for details.\n' - '\n' - '**Programmer’s note:** Variables defined in the class definition ' - 'are\n' - 'class attributes; they are shared by instances. Instance ' - 'attributes\n' - 'can be set in a method with "self.name = value". Both class ' - 'and\n' - 'instance attributes are accessible through the notation ' - '“"self.name"”,\n' - 'and an instance attribute hides a class attribute with the same ' - 'name\n' - 'when accessed in this way. Class attributes can be used as ' - 'defaults\n' - 'for instance attributes, but using mutable values there can lead ' - 'to\n' - 'unexpected results. Descriptors can be used to create instance\n' - 'variables with different implementation details.\n' - '\n' - 'See also:\n' - '\n' - ' **PEP 3115** - Metaclasses in Python 3000\n' - ' The proposal that changed the declaration of metaclasses to ' - 'the\n' - ' current syntax, and the semantics for how classes with\n' - ' metaclasses are constructed.\n' - '\n' - ' **PEP 3129** - Class Decorators\n' - ' The proposal that added class decorators. Function and ' - 'method\n' - ' decorators were introduced in **PEP 318**.\n' - '\n' - '\n' - 'Coroutines\n' - '==========\n' - '\n' - 'New in version 3.5.\n' - '\n' - '\n' - 'Coroutine function definition\n' - '-----------------------------\n' - '\n' - ' async_funcdef ::= [decorators] "async" "def" funcname "(" ' - '[parameter_list] ")"\n' - ' ["->" expression] ":" suite\n' - '\n' - 'Execution of Python coroutines can be suspended and resumed at ' - 'many\n' - 'points (see *coroutine*). "await" expressions, "async for" and ' - '"async\n' - 'with" can only be used in the body of a coroutine function.\n' - '\n' - 'Functions defined with "async def" syntax are always coroutine\n' - 'functions, even if they do not contain "await" or "async" ' - 'keywords.\n' - '\n' - 'It is a "SyntaxError" to use a "yield from" expression inside ' - 'the body\n' - 'of a coroutine function.\n' - '\n' - 'An example of a coroutine function:\n' - '\n' - ' async def func(param1, param2):\n' - ' do_stuff()\n' - ' await some_coroutine()\n' - '\n' - 'Changed in version 3.7: "await" and "async" are now keywords;\n' - 'previously they were only treated as such inside the body of a\n' - 'coroutine function.\n' - '\n' - '\n' - 'The "async for" statement\n' - '-------------------------\n' - '\n' - ' async_for_stmt ::= "async" for_stmt\n' - '\n' - 'An *asynchronous iterable* provides an "__aiter__" method that\n' - 'directly returns an *asynchronous iterator*, which can call\n' - 'asynchronous code in its "__anext__" method.\n' - '\n' - 'The "async for" statement allows convenient iteration over\n' - 'asynchronous iterables.\n' - '\n' - 'The following code:\n' - '\n' - ' async for TARGET in ITER:\n' - ' SUITE\n' - ' else:\n' - ' SUITE2\n' - '\n' - 'Is semantically equivalent to:\n' - '\n' - ' iter = (ITER)\n' - ' iter = type(iter).__aiter__(iter)\n' - ' running = True\n' - '\n' - ' while running:\n' - ' try:\n' - ' TARGET = await type(iter).__anext__(iter)\n' - ' except StopAsyncIteration:\n' - ' running = False\n' - ' else:\n' - ' SUITE\n' - ' else:\n' - ' SUITE2\n' - '\n' - 'See also "__aiter__()" and "__anext__()" for details.\n' - '\n' - 'It is a "SyntaxError" to use an "async for" statement outside ' - 'the body\n' - 'of a coroutine function.\n' - '\n' - '\n' - 'The "async with" statement\n' - '--------------------------\n' - '\n' - ' async_with_stmt ::= "async" with_stmt\n' - '\n' - 'An *asynchronous context manager* is a *context manager* that is ' - 'able\n' - 'to suspend execution in its *enter* and *exit* methods.\n' - '\n' - 'The following code:\n' - '\n' - ' async with EXPRESSION as TARGET:\n' - ' SUITE\n' - '\n' - 'is semantically equivalent to:\n' - '\n' - ' manager = (EXPRESSION)\n' - ' aenter = type(manager).__aenter__\n' - ' aexit = type(manager).__aexit__\n' - ' value = await aenter(manager)\n' - ' hit_except = False\n' - '\n' - ' try:\n' - ' TARGET = value\n' - ' SUITE\n' - ' except:\n' - ' hit_except = True\n' - ' if not await aexit(manager, *sys.exc_info()):\n' - ' raise\n' - ' finally:\n' - ' if not hit_except:\n' - ' await aexit(manager, None, None, None)\n' - '\n' - 'See also "__aenter__()" and "__aexit__()" for details.\n' - '\n' - 'It is a "SyntaxError" to use an "async with" statement outside ' - 'the\n' - 'body of a coroutine function.\n' - '\n' - 'See also:\n' - '\n' - ' **PEP 492** - Coroutines with async and await syntax\n' - ' The proposal that made coroutines a proper standalone ' - 'concept in\n' - ' Python, and added supporting syntax.\n' - '\n' - '-[ Footnotes ]-\n' - '\n' - '[1] The exception is propagated to the invocation stack unless ' - 'there\n' - ' is a "finally" clause which happens to raise another ' - 'exception.\n' - ' That new exception causes the old one to be lost.\n' - '\n' - '[2] In pattern matching, a sequence is defined as one of the\n' - ' following:\n' - '\n' - ' * a class that inherits from "collections.abc.Sequence"\n' - '\n' - ' * a Python class that has been registered as\n' - ' "collections.abc.Sequence"\n' - '\n' - ' * a builtin class that has its (CPython) ' - '"Py_TPFLAGS_SEQUENCE"\n' - ' bit set\n' - '\n' - ' * a class that inherits from any of the above\n' - '\n' - ' The following standard library classes are sequences:\n' - '\n' - ' * "array.array"\n' - '\n' - ' * "collections.deque"\n' - '\n' - ' * "list"\n' - '\n' - ' * "memoryview"\n' - '\n' - ' * "range"\n' - '\n' - ' * "tuple"\n' - '\n' - ' Note:\n' - '\n' - ' Subject values of type "str", "bytes", and "bytearray" do ' - 'not\n' - ' match sequence patterns.\n' - '\n' - '[3] In pattern matching, a mapping is defined as one of the ' - 'following:\n' - '\n' - ' * a class that inherits from "collections.abc.Mapping"\n' - '\n' - ' * a Python class that has been registered as\n' - ' "collections.abc.Mapping"\n' - '\n' - ' * a builtin class that has its (CPython) ' - '"Py_TPFLAGS_MAPPING"\n' - ' bit set\n' - '\n' - ' * a class that inherits from any of the above\n' - '\n' - ' The standard library classes "dict" and ' - '"types.MappingProxyType"\n' - ' are mappings.\n' - '\n' - '[4] A string literal appearing as the first statement in the ' - 'function\n' - ' body is transformed into the function’s "__doc__" attribute ' - 'and\n' - ' therefore the function’s *docstring*.\n' - '\n' - '[5] A string literal appearing as the first statement in the ' - 'class\n' - ' body is transformed into the namespace’s "__doc__" item and\n' - ' therefore the class’s *docstring*.\n', - 'context-managers': 'With Statement Context Managers\n' - '*******************************\n' - '\n' - 'A *context manager* is an object that defines the ' - 'runtime context to\n' - 'be established when executing a "with" statement. The ' - 'context manager\n' - 'handles the entry into, and the exit from, the desired ' - 'runtime context\n' - 'for the execution of the block of code. Context ' - 'managers are normally\n' - 'invoked using the "with" statement (described in section ' - 'The with\n' - 'statement), but can also be used by directly invoking ' - 'their methods.\n' - '\n' - 'Typical uses of context managers include saving and ' - 'restoring various\n' - 'kinds of global state, locking and unlocking resources, ' - 'closing opened\n' - 'files, etc.\n' - '\n' - 'For more information on context managers, see Context ' - 'Manager Types.\n' - '\n' - 'object.__enter__(self)\n' - '\n' - ' Enter the runtime context related to this object. The ' - '"with"\n' - ' statement will bind this method’s return value to the ' - 'target(s)\n' - ' specified in the "as" clause of the statement, if ' - 'any.\n' - '\n' - 'object.__exit__(self, exc_type, exc_value, traceback)\n' - '\n' - ' Exit the runtime context related to this object. The ' - 'parameters\n' - ' describe the exception that caused the context to be ' - 'exited. If the\n' - ' context was exited without an exception, all three ' - 'arguments will\n' - ' be "None".\n' - '\n' - ' If an exception is supplied, and the method wishes to ' - 'suppress the\n' - ' exception (i.e., prevent it from being propagated), ' - 'it should\n' - ' return a true value. Otherwise, the exception will be ' - 'processed\n' - ' normally upon exit from this method.\n' - '\n' - ' Note that "__exit__()" methods should not reraise the ' - 'passed-in\n' - ' exception; this is the caller’s responsibility.\n' - '\n' - 'See also:\n' - '\n' - ' **PEP 343** - The “with” statement\n' - ' The specification, background, and examples for the ' - 'Python "with"\n' - ' statement.\n', - 'continue': 'The "continue" statement\n' - '************************\n' - '\n' - ' continue_stmt ::= "continue"\n' - '\n' - '"continue" may only occur syntactically nested in a "for" or ' - '"while"\n' - 'loop, but not nested in a function or class definition within ' - 'that\n' - 'loop. It continues with the next cycle of the nearest enclosing ' - 'loop.\n' - '\n' - 'When "continue" passes control out of a "try" statement with a\n' - '"finally" clause, that "finally" clause is executed before ' - 'really\n' - 'starting the next loop cycle.\n', - 'conversions': 'Arithmetic conversions\n' - '**********************\n' - '\n' - 'When a description of an arithmetic operator below uses the ' - 'phrase\n' - '“the numeric arguments are converted to a common type”, this ' - 'means\n' - 'that the operator implementation for built-in types works as ' - 'follows:\n' - '\n' - '* If either argument is a complex number, the other is ' - 'converted to\n' - ' complex;\n' - '\n' - '* otherwise, if either argument is a floating point number, ' - 'the other\n' - ' is converted to floating point;\n' - '\n' - '* otherwise, both must be integers and no conversion is ' - 'necessary.\n' - '\n' - 'Some additional rules apply for certain operators (e.g., a ' - 'string as a\n' - 'left argument to the ‘%’ operator). Extensions must define ' - 'their own\n' - 'conversion behavior.\n', - 'customization': 'Basic customization\n' - '*******************\n' - '\n' - 'object.__new__(cls[, ...])\n' - '\n' - ' Called to create a new instance of class *cls*. ' - '"__new__()" is a\n' - ' static method (special-cased so you need not declare it ' - 'as such)\n' - ' that takes the class of which an instance was requested ' - 'as its\n' - ' first argument. The remaining arguments are those ' - 'passed to the\n' - ' object constructor expression (the call to the class). ' - 'The return\n' - ' value of "__new__()" should be the new object instance ' - '(usually an\n' - ' instance of *cls*).\n' - '\n' - ' Typical implementations create a new instance of the ' - 'class by\n' - ' invoking the superclass’s "__new__()" method using\n' - ' "super().__new__(cls[, ...])" with appropriate arguments ' - 'and then\n' - ' modifying the newly-created instance as necessary before ' - 'returning\n' - ' it.\n' - '\n' - ' If "__new__()" is invoked during object construction and ' - 'it returns\n' - ' an instance of *cls*, then the new instance’s ' - '"__init__()" method\n' - ' will be invoked like "__init__(self[, ...])", where ' - '*self* is the\n' - ' new instance and the remaining arguments are the same as ' - 'were\n' - ' passed to the object constructor.\n' - '\n' - ' If "__new__()" does not return an instance of *cls*, ' - 'then the new\n' - ' instance’s "__init__()" method will not be invoked.\n' - '\n' - ' "__new__()" is intended mainly to allow subclasses of ' - 'immutable\n' - ' types (like int, str, or tuple) to customize instance ' - 'creation. It\n' - ' is also commonly overridden in custom metaclasses in ' - 'order to\n' - ' customize class creation.\n' - '\n' - 'object.__init__(self[, ...])\n' - '\n' - ' Called after the instance has been created (by ' - '"__new__()"), but\n' - ' before it is returned to the caller. The arguments are ' - 'those\n' - ' passed to the class constructor expression. If a base ' - 'class has an\n' - ' "__init__()" method, the derived class’s "__init__()" ' - 'method, if\n' - ' any, must explicitly call it to ensure proper ' - 'initialization of the\n' - ' base class part of the instance; for example:\n' - ' "super().__init__([args...])".\n' - '\n' - ' Because "__new__()" and "__init__()" work together in ' - 'constructing\n' - ' objects ("__new__()" to create it, and "__init__()" to ' - 'customize\n' - ' it), no non-"None" value may be returned by ' - '"__init__()"; doing so\n' - ' will cause a "TypeError" to be raised at runtime.\n' - '\n' - 'object.__del__(self)\n' - '\n' - ' Called when the instance is about to be destroyed. This ' - 'is also\n' - ' called a finalizer or (improperly) a destructor. If a ' - 'base class\n' - ' has a "__del__()" method, the derived class’s ' - '"__del__()" method,\n' - ' if any, must explicitly call it to ensure proper ' - 'deletion of the\n' - ' base class part of the instance.\n' - '\n' - ' It is possible (though not recommended!) for the ' - '"__del__()" method\n' - ' to postpone destruction of the instance by creating a ' - 'new reference\n' - ' to it. This is called object *resurrection*. It is\n' - ' implementation-dependent whether "__del__()" is called a ' - 'second\n' - ' time when a resurrected object is about to be destroyed; ' - 'the\n' - ' current *CPython* implementation only calls it once.\n' - '\n' - ' It is not guaranteed that "__del__()" methods are called ' - 'for\n' - ' objects that still exist when the interpreter exits.\n' - '\n' - ' Note:\n' - '\n' - ' "del x" doesn’t directly call "x.__del__()" — the ' - 'former\n' - ' decrements the reference count for "x" by one, and the ' - 'latter is\n' - ' only called when "x"’s reference count reaches zero.\n' - '\n' - ' **CPython implementation detail:** It is possible for a ' - 'reference\n' - ' cycle to prevent the reference count of an object from ' - 'going to\n' - ' zero. In this case, the cycle will be later detected ' - 'and deleted\n' - ' by the *cyclic garbage collector*. A common cause of ' - 'reference\n' - ' cycles is when an exception has been caught in a local ' - 'variable.\n' - ' The frame’s locals then reference the exception, which ' - 'references\n' - ' its own traceback, which references the locals of all ' - 'frames caught\n' - ' in the traceback.\n' - '\n' - ' See also: Documentation for the "gc" module.\n' - '\n' - ' Warning:\n' - '\n' - ' Due to the precarious circumstances under which ' - '"__del__()"\n' - ' methods are invoked, exceptions that occur during ' - 'their execution\n' - ' are ignored, and a warning is printed to "sys.stderr" ' - 'instead.\n' - ' In particular:\n' - '\n' - ' * "__del__()" can be invoked when arbitrary code is ' - 'being\n' - ' executed, including from any arbitrary thread. If ' - '"__del__()"\n' - ' needs to take a lock or invoke any other blocking ' - 'resource, it\n' - ' may deadlock as the resource may already be taken by ' - 'the code\n' - ' that gets interrupted to execute "__del__()".\n' - '\n' - ' * "__del__()" can be executed during interpreter ' - 'shutdown. As a\n' - ' consequence, the global variables it needs to access ' - '(including\n' - ' other modules) may already have been deleted or set ' - 'to "None".\n' - ' Python guarantees that globals whose name begins ' - 'with a single\n' - ' underscore are deleted from their module before ' - 'other globals\n' - ' are deleted; if no other references to such globals ' - 'exist, this\n' - ' may help in assuring that imported modules are still ' - 'available\n' - ' at the time when the "__del__()" method is called.\n' - '\n' - 'object.__repr__(self)\n' - '\n' - ' Called by the "repr()" built-in function to compute the ' - '“official”\n' - ' string representation of an object. If at all possible, ' - 'this\n' - ' should look like a valid Python expression that could be ' - 'used to\n' - ' recreate an object with the same value (given an ' - 'appropriate\n' - ' environment). If this is not possible, a string of the ' - 'form\n' - ' "<...some useful description...>" should be returned. ' - 'The return\n' - ' value must be a string object. If a class defines ' - '"__repr__()" but\n' - ' not "__str__()", then "__repr__()" is also used when an ' - '“informal”\n' - ' string representation of instances of that class is ' - 'required.\n' - '\n' - ' This is typically used for debugging, so it is important ' - 'that the\n' - ' representation is information-rich and unambiguous.\n' - '\n' - 'object.__str__(self)\n' - '\n' - ' Called by "str(object)" and the built-in functions ' - '"format()" and\n' - ' "print()" to compute the “informal” or nicely printable ' - 'string\n' - ' representation of an object. The return value must be a ' - 'string\n' - ' object.\n' - '\n' - ' This method differs from "object.__repr__()" in that ' - 'there is no\n' - ' expectation that "__str__()" return a valid Python ' - 'expression: a\n' - ' more convenient or concise representation can be used.\n' - '\n' - ' The default implementation defined by the built-in type ' - '"object"\n' - ' calls "object.__repr__()".\n' - '\n' - 'object.__bytes__(self)\n' - '\n' - ' Called by bytes to compute a byte-string representation ' - 'of an\n' - ' object. This should return a "bytes" object.\n' - '\n' - 'object.__format__(self, format_spec)\n' - '\n' - ' Called by the "format()" built-in function, and by ' - 'extension,\n' - ' evaluation of formatted string literals and the ' - '"str.format()"\n' - ' method, to produce a “formatted” string representation ' - 'of an\n' - ' object. The *format_spec* argument is a string that ' - 'contains a\n' - ' description of the formatting options desired. The ' - 'interpretation\n' - ' of the *format_spec* argument is up to the type ' - 'implementing\n' - ' "__format__()", however most classes will either ' - 'delegate\n' - ' formatting to one of the built-in types, or use a ' - 'similar\n' - ' formatting option syntax.\n' - '\n' - ' See Format Specification Mini-Language for a description ' - 'of the\n' - ' standard formatting syntax.\n' - '\n' - ' The return value must be a string object.\n' - '\n' - ' Changed in version 3.4: The __format__ method of ' - '"object" itself\n' - ' raises a "TypeError" if passed any non-empty string.\n' - '\n' - ' Changed in version 3.7: "object.__format__(x, \'\')" is ' - 'now\n' - ' equivalent to "str(x)" rather than "format(str(x), ' - '\'\')".\n' - '\n' - 'object.__lt__(self, other)\n' - 'object.__le__(self, other)\n' - 'object.__eq__(self, other)\n' - 'object.__ne__(self, other)\n' - 'object.__gt__(self, other)\n' - 'object.__ge__(self, other)\n' - '\n' - ' These are the so-called “rich comparison” methods. The\n' - ' correspondence between operator symbols and method names ' - 'is as\n' - ' follows: "x<y" calls "x.__lt__(y)", "x<=y" calls ' - '"x.__le__(y)",\n' - ' "x==y" calls "x.__eq__(y)", "x!=y" calls "x.__ne__(y)", ' - '"x>y" calls\n' - ' "x.__gt__(y)", and "x>=y" calls "x.__ge__(y)".\n' - '\n' - ' A rich comparison method may return the singleton ' - '"NotImplemented"\n' - ' if it does not implement the operation for a given pair ' - 'of\n' - ' arguments. By convention, "False" and "True" are ' - 'returned for a\n' - ' successful comparison. However, these methods can return ' - 'any value,\n' - ' so if the comparison operator is used in a Boolean ' - 'context (e.g.,\n' - ' in the condition of an "if" statement), Python will call ' - '"bool()"\n' - ' on the value to determine if the result is true or ' - 'false.\n' - '\n' - ' By default, "object" implements "__eq__()" by using ' - '"is", returning\n' - ' "NotImplemented" in the case of a false comparison: ' - '"True if x is y\n' - ' else NotImplemented". For "__ne__()", by default it ' - 'delegates to\n' - ' "__eq__()" and inverts the result unless it is ' - '"NotImplemented".\n' - ' There are no other implied relationships among the ' - 'comparison\n' - ' operators or default implementations; for example, the ' - 'truth of\n' - ' "(x<y or x==y)" does not imply "x<=y". To automatically ' - 'generate\n' - ' ordering operations from a single root operation, see\n' - ' "functools.total_ordering()".\n' - '\n' - ' See the paragraph on "__hash__()" for some important ' - 'notes on\n' - ' creating *hashable* objects which support custom ' - 'comparison\n' - ' operations and are usable as dictionary keys.\n' - '\n' - ' There are no swapped-argument versions of these methods ' - '(to be used\n' - ' when the left argument does not support the operation ' - 'but the right\n' - ' argument does); rather, "__lt__()" and "__gt__()" are ' - 'each other’s\n' - ' reflection, "__le__()" and "__ge__()" are each other’s ' - 'reflection,\n' - ' and "__eq__()" and "__ne__()" are their own reflection. ' - 'If the\n' - ' operands are of different types, and right operand’s ' - 'type is a\n' - ' direct or indirect subclass of the left operand’s type, ' - 'the\n' - ' reflected method of the right operand has priority, ' - 'otherwise the\n' - ' left operand’s method has priority. Virtual subclassing ' - 'is not\n' - ' considered.\n' - '\n' - 'object.__hash__(self)\n' - '\n' - ' Called by built-in function "hash()" and for operations ' - 'on members\n' - ' of hashed collections including "set", "frozenset", and ' - '"dict".\n' - ' The "__hash__()" method should return an integer. The ' - 'only required\n' - ' property is that objects which compare equal have the ' - 'same hash\n' - ' value; it is advised to mix together the hash values of ' - 'the\n' - ' components of the object that also play a part in ' - 'comparison of\n' - ' objects by packing them into a tuple and hashing the ' - 'tuple.\n' - ' Example:\n' - '\n' - ' def __hash__(self):\n' - ' return hash((self.name, self.nick, self.color))\n' - '\n' - ' Note:\n' - '\n' - ' "hash()" truncates the value returned from an object’s ' - 'custom\n' - ' "__hash__()" method to the size of a "Py_ssize_t". ' - 'This is\n' - ' typically 8 bytes on 64-bit builds and 4 bytes on ' - '32-bit builds.\n' - ' If an object’s "__hash__()" must interoperate on ' - 'builds of\n' - ' different bit sizes, be sure to check the width on all ' - 'supported\n' - ' builds. An easy way to do this is with "python -c ' - '"import sys;\n' - ' print(sys.hash_info.width)"".\n' - '\n' - ' If a class does not define an "__eq__()" method it ' - 'should not\n' - ' define a "__hash__()" operation either; if it defines ' - '"__eq__()"\n' - ' but not "__hash__()", its instances will not be usable ' - 'as items in\n' - ' hashable collections. If a class defines mutable ' - 'objects and\n' - ' implements an "__eq__()" method, it should not ' - 'implement\n' - ' "__hash__()", since the implementation of hashable ' - 'collections\n' - ' requires that a key’s hash value is immutable (if the ' - 'object’s hash\n' - ' value changes, it will be in the wrong hash bucket).\n' - '\n' - ' User-defined classes have "__eq__()" and "__hash__()" ' - 'methods by\n' - ' default; with them, all objects compare unequal (except ' - 'with\n' - ' themselves) and "x.__hash__()" returns an appropriate ' - 'value such\n' - ' that "x == y" implies both that "x is y" and "hash(x) == ' - 'hash(y)".\n' - '\n' - ' A class that overrides "__eq__()" and does not define ' - '"__hash__()"\n' - ' will have its "__hash__()" implicitly set to "None". ' - 'When the\n' - ' "__hash__()" method of a class is "None", instances of ' - 'the class\n' - ' will raise an appropriate "TypeError" when a program ' - 'attempts to\n' - ' retrieve their hash value, and will also be correctly ' - 'identified as\n' - ' unhashable when checking "isinstance(obj,\n' - ' collections.abc.Hashable)".\n' - '\n' - ' If a class that overrides "__eq__()" needs to retain ' - 'the\n' - ' implementation of "__hash__()" from a parent class, the ' - 'interpreter\n' - ' must be told this explicitly by setting "__hash__ =\n' - ' <ParentClass>.__hash__".\n' - '\n' - ' If a class that does not override "__eq__()" wishes to ' - 'suppress\n' - ' hash support, it should include "__hash__ = None" in the ' - 'class\n' - ' definition. A class which defines its own "__hash__()" ' - 'that\n' - ' explicitly raises a "TypeError" would be incorrectly ' - 'identified as\n' - ' hashable by an "isinstance(obj, ' - 'collections.abc.Hashable)" call.\n' - '\n' - ' Note:\n' - '\n' - ' By default, the "__hash__()" values of str and bytes ' - 'objects are\n' - ' “salted” with an unpredictable random value. Although ' - 'they\n' - ' remain constant within an individual Python process, ' - 'they are not\n' - ' predictable between repeated invocations of ' - 'Python.This is\n' - ' intended to provide protection against a ' - 'denial-of-service caused\n' - ' by carefully-chosen inputs that exploit the worst ' - 'case\n' - ' performance of a dict insertion, O(n^2) complexity. ' - 'See\n' - ' http://www.ocert.org/advisories/ocert-2011-003.html ' - 'for\n' - ' details.Changing hash values affects the iteration ' - 'order of sets.\n' - ' Python has never made guarantees about this ordering ' - '(and it\n' - ' typically varies between 32-bit and 64-bit builds).See ' - 'also\n' - ' "PYTHONHASHSEED".\n' - '\n' - ' Changed in version 3.3: Hash randomization is enabled by ' - 'default.\n' - '\n' - 'object.__bool__(self)\n' - '\n' - ' Called to implement truth value testing and the built-in ' - 'operation\n' - ' "bool()"; should return "False" or "True". When this ' - 'method is not\n' - ' defined, "__len__()" is called, if it is defined, and ' - 'the object is\n' - ' considered true if its result is nonzero. If a class ' - 'defines\n' - ' neither "__len__()" nor "__bool__()", all its instances ' - 'are\n' - ' considered true.\n', - 'debugger': '"pdb" — The Python Debugger\n' - '***************************\n' - '\n' - '**Source code:** Lib/pdb.py\n' - '\n' - '======================================================================\n' - '\n' - 'The module "pdb" defines an interactive source code debugger ' - 'for\n' - 'Python programs. It supports setting (conditional) breakpoints ' - 'and\n' - 'single stepping at the source line level, inspection of stack ' - 'frames,\n' - 'source code listing, and evaluation of arbitrary Python code in ' - 'the\n' - 'context of any stack frame. It also supports post-mortem ' - 'debugging\n' - 'and can be called under program control.\n' - '\n' - 'The debugger is extensible – it is actually defined as the ' - 'class\n' - '"Pdb". This is currently undocumented but easily understood by ' - 'reading\n' - 'the source. The extension interface uses the modules "bdb" and ' - '"cmd".\n' - '\n' - 'The debugger’s prompt is "(Pdb)". Typical usage to run a program ' - 'under\n' - 'control of the debugger is:\n' - '\n' - ' >>> import pdb\n' - ' >>> import mymodule\n' - " >>> pdb.run('mymodule.test()')\n" - ' > <string>(0)?()\n' - ' (Pdb) continue\n' - ' > <string>(1)?()\n' - ' (Pdb) continue\n' - " NameError: 'spam'\n" - ' > <string>(1)?()\n' - ' (Pdb)\n' - '\n' - 'Changed in version 3.3: Tab-completion via the "readline" module ' - 'is\n' - 'available for commands and command arguments, e.g. the current ' - 'global\n' - 'and local names are offered as arguments of the "p" command.\n' - '\n' - '"pdb.py" can also be invoked as a script to debug other ' - 'scripts. For\n' - 'example:\n' - '\n' - ' python3 -m pdb myscript.py\n' - '\n' - 'When invoked as a script, pdb will automatically enter ' - 'post-mortem\n' - 'debugging if the program being debugged exits abnormally. After ' - 'post-\n' - 'mortem debugging (or after normal exit of the program), pdb ' - 'will\n' - 'restart the program. Automatic restarting preserves pdb’s state ' - '(such\n' - 'as breakpoints) and in most cases is more useful than quitting ' - 'the\n' - 'debugger upon program’s exit.\n' - '\n' - 'New in version 3.2: "pdb.py" now accepts a "-c" option that ' - 'executes\n' - 'commands as if given in a ".pdbrc" file, see Debugger Commands.\n' - '\n' - 'New in version 3.7: "pdb.py" now accepts a "-m" option that ' - 'execute\n' - 'modules similar to the way "python3 -m" does. As with a script, ' - 'the\n' - 'debugger will pause execution just before the first line of the\n' - 'module.\n' - '\n' - 'The typical usage to break into the debugger is to insert:\n' - '\n' - ' import pdb; pdb.set_trace()\n' - '\n' - 'at the location you want to break into the debugger, and then ' - 'run the\n' - 'program. You can then step through the code following this ' - 'statement,\n' - 'and continue running without the debugger using the "continue"\n' - 'command.\n' - '\n' - 'New in version 3.7: The built-in "breakpoint()", when called ' - 'with\n' - 'defaults, can be used instead of "import pdb; pdb.set_trace()".\n' - '\n' - 'The typical usage to inspect a crashed program is:\n' - '\n' - ' >>> import pdb\n' - ' >>> import mymodule\n' - ' >>> mymodule.test()\n' - ' Traceback (most recent call last):\n' - ' File "<stdin>", line 1, in <module>\n' - ' File "./mymodule.py", line 4, in test\n' - ' test2()\n' - ' File "./mymodule.py", line 3, in test2\n' - ' print(spam)\n' - ' NameError: spam\n' - ' >>> pdb.pm()\n' - ' > ./mymodule.py(3)test2()\n' - ' -> print(spam)\n' - ' (Pdb)\n' - '\n' - 'The module defines the following functions; each enters the ' - 'debugger\n' - 'in a slightly different way:\n' - '\n' - 'pdb.run(statement, globals=None, locals=None)\n' - '\n' - ' Execute the *statement* (given as a string or a code object) ' - 'under\n' - ' debugger control. The debugger prompt appears before any ' - 'code is\n' - ' executed; you can set breakpoints and type "continue", or you ' - 'can\n' - ' step through the statement using "step" or "next" (all these\n' - ' commands are explained below). The optional *globals* and ' - '*locals*\n' - ' arguments specify the environment in which the code is ' - 'executed; by\n' - ' default the dictionary of the module "__main__" is used. ' - '(See the\n' - ' explanation of the built-in "exec()" or "eval()" functions.)\n' - '\n' - 'pdb.runeval(expression, globals=None, locals=None)\n' - '\n' - ' Evaluate the *expression* (given as a string or a code ' - 'object)\n' - ' under debugger control. When "runeval()" returns, it returns ' - 'the\n' - ' value of the expression. Otherwise this function is similar ' - 'to\n' - ' "run()".\n' - '\n' - 'pdb.runcall(function, *args, **kwds)\n' - '\n' - ' Call the *function* (a function or method object, not a ' - 'string)\n' - ' with the given arguments. When "runcall()" returns, it ' - 'returns\n' - ' whatever the function call returned. The debugger prompt ' - 'appears\n' - ' as soon as the function is entered.\n' - '\n' - 'pdb.set_trace(*, header=None)\n' - '\n' - ' Enter the debugger at the calling stack frame. This is ' - 'useful to\n' - ' hard-code a breakpoint at a given point in a program, even if ' - 'the\n' - ' code is not otherwise being debugged (e.g. when an assertion\n' - ' fails). If given, *header* is printed to the console just ' - 'before\n' - ' debugging begins.\n' - '\n' - ' Changed in version 3.7: The keyword-only argument *header*.\n' - '\n' - 'pdb.post_mortem(traceback=None)\n' - '\n' - ' Enter post-mortem debugging of the given *traceback* object. ' - 'If no\n' - ' *traceback* is given, it uses the one of the exception that ' - 'is\n' - ' currently being handled (an exception must be being handled ' - 'if the\n' - ' default is to be used).\n' - '\n' - 'pdb.pm()\n' - '\n' - ' Enter post-mortem debugging of the traceback found in\n' - ' "sys.last_traceback".\n' - '\n' - 'The "run*" functions and "set_trace()" are aliases for ' - 'instantiating\n' - 'the "Pdb" class and calling the method of the same name. If you ' - 'want\n' - 'to access further features, you have to do this yourself:\n' - '\n' - "class pdb.Pdb(completekey='tab', stdin=None, stdout=None, " - 'skip=None, nosigint=False, readrc=True)\n' - '\n' - ' "Pdb" is the debugger class.\n' - '\n' - ' The *completekey*, *stdin* and *stdout* arguments are passed ' - 'to the\n' - ' underlying "cmd.Cmd" class; see the description there.\n' - '\n' - ' The *skip* argument, if given, must be an iterable of ' - 'glob-style\n' - ' module name patterns. The debugger will not step into frames ' - 'that\n' - ' originate in a module that matches one of these patterns. ' - '[1]\n' - '\n' - ' By default, Pdb sets a handler for the SIGINT signal (which ' - 'is sent\n' - ' when the user presses "Ctrl-C" on the console) when you give ' - 'a\n' - ' "continue" command. This allows you to break into the ' - 'debugger\n' - ' again by pressing "Ctrl-C". If you want Pdb not to touch ' - 'the\n' - ' SIGINT handler, set *nosigint* to true.\n' - '\n' - ' The *readrc* argument defaults to true and controls whether ' - 'Pdb\n' - ' will load .pdbrc files from the filesystem.\n' - '\n' - ' Example call to enable tracing with *skip*:\n' - '\n' - " import pdb; pdb.Pdb(skip=['django.*']).set_trace()\n" - '\n' - ' Raises an auditing event "pdb.Pdb" with no arguments.\n' - '\n' - ' New in version 3.1: The *skip* argument.\n' - '\n' - ' New in version 3.2: The *nosigint* argument. Previously, a ' - 'SIGINT\n' - ' handler was never set by Pdb.\n' - '\n' - ' Changed in version 3.6: The *readrc* argument.\n' - '\n' - ' run(statement, globals=None, locals=None)\n' - ' runeval(expression, globals=None, locals=None)\n' - ' runcall(function, *args, **kwds)\n' - ' set_trace()\n' - '\n' - ' See the documentation for the functions explained above.\n' - '\n' - '\n' - 'Debugger Commands\n' - '=================\n' - '\n' - 'The commands recognized by the debugger are listed below. Most\n' - 'commands can be abbreviated to one or two letters as indicated; ' - 'e.g.\n' - '"h(elp)" means that either "h" or "help" can be used to enter ' - 'the help\n' - 'command (but not "he" or "hel", nor "H" or "Help" or "HELP").\n' - 'Arguments to commands must be separated by whitespace (spaces ' - 'or\n' - 'tabs). Optional arguments are enclosed in square brackets ' - '("[]") in\n' - 'the command syntax; the square brackets must not be typed.\n' - 'Alternatives in the command syntax are separated by a vertical ' - 'bar\n' - '("|").\n' - '\n' - 'Entering a blank line repeats the last command entered. ' - 'Exception: if\n' - 'the last command was a "list" command, the next 11 lines are ' - 'listed.\n' - '\n' - 'Commands that the debugger doesn’t recognize are assumed to be ' - 'Python\n' - 'statements and are executed in the context of the program being\n' - 'debugged. Python statements can also be prefixed with an ' - 'exclamation\n' - 'point ("!"). This is a powerful way to inspect the program ' - 'being\n' - 'debugged; it is even possible to change a variable or call a ' - 'function.\n' - 'When an exception occurs in such a statement, the exception name ' - 'is\n' - 'printed but the debugger’s state is not changed.\n' - '\n' - 'The debugger supports aliases. Aliases can have parameters ' - 'which\n' - 'allows one a certain level of adaptability to the context under\n' - 'examination.\n' - '\n' - 'Multiple commands may be entered on a single line, separated by ' - '";;".\n' - '(A single ";" is not used as it is the separator for multiple ' - 'commands\n' - 'in a line that is passed to the Python parser.) No intelligence ' - 'is\n' - 'applied to separating the commands; the input is split at the ' - 'first\n' - '";;" pair, even if it is in the middle of a quoted string. A\n' - 'workaround for strings with double semicolons is to use ' - 'implicit\n' - 'string concatenation "\';\'\';\'" or "";"";"".\n' - '\n' - 'If a file ".pdbrc" exists in the user’s home directory or in ' - 'the\n' - 'current directory, it is read in and executed as if it had been ' - 'typed\n' - 'at the debugger prompt. This is particularly useful for ' - 'aliases. If\n' - 'both files exist, the one in the home directory is read first ' - 'and\n' - 'aliases defined there can be overridden by the local file.\n' - '\n' - 'Changed in version 3.2: ".pdbrc" can now contain commands that\n' - 'continue debugging, such as "continue" or "next". Previously, ' - 'these\n' - 'commands had no effect.\n' - '\n' - 'h(elp) [command]\n' - '\n' - ' Without argument, print the list of available commands. With ' - 'a\n' - ' *command* as argument, print help about that command. "help ' - 'pdb"\n' - ' displays the full documentation (the docstring of the "pdb"\n' - ' module). Since the *command* argument must be an identifier, ' - '"help\n' - ' exec" must be entered to get help on the "!" command.\n' - '\n' - 'w(here)\n' - '\n' - ' Print a stack trace, with the most recent frame at the ' - 'bottom. An\n' - ' arrow indicates the current frame, which determines the ' - 'context of\n' - ' most commands.\n' - '\n' - 'd(own) [count]\n' - '\n' - ' Move the current frame *count* (default one) levels down in ' - 'the\n' - ' stack trace (to a newer frame).\n' - '\n' - 'u(p) [count]\n' - '\n' - ' Move the current frame *count* (default one) levels up in the ' - 'stack\n' - ' trace (to an older frame).\n' - '\n' - 'b(reak) [([filename:]lineno | function) [, condition]]\n' - '\n' - ' With a *lineno* argument, set a break there in the current ' - 'file.\n' - ' With a *function* argument, set a break at the first ' - 'executable\n' - ' statement within that function. The line number may be ' - 'prefixed\n' - ' with a filename and a colon, to specify a breakpoint in ' - 'another\n' - ' file (probably one that hasn’t been loaded yet). The file ' - 'is\n' - ' searched on "sys.path". Note that each breakpoint is ' - 'assigned a\n' - ' number to which all the other breakpoint commands refer.\n' - '\n' - ' If a second argument is present, it is an expression which ' - 'must\n' - ' evaluate to true before the breakpoint is honored.\n' - '\n' - ' Without argument, list all breaks, including for each ' - 'breakpoint,\n' - ' the number of times that breakpoint has been hit, the ' - 'current\n' - ' ignore count, and the associated condition if any.\n' - '\n' - 'tbreak [([filename:]lineno | function) [, condition]]\n' - '\n' - ' Temporary breakpoint, which is removed automatically when it ' - 'is\n' - ' first hit. The arguments are the same as for "break".\n' - '\n' - 'cl(ear) [filename:lineno | bpnumber ...]\n' - '\n' - ' With a *filename:lineno* argument, clear all the breakpoints ' - 'at\n' - ' this line. With a space separated list of breakpoint numbers, ' - 'clear\n' - ' those breakpoints. Without argument, clear all breaks (but ' - 'first\n' - ' ask confirmation).\n' - '\n' - 'disable [bpnumber ...]\n' - '\n' - ' Disable the breakpoints given as a space separated list of\n' - ' breakpoint numbers. Disabling a breakpoint means it cannot ' - 'cause\n' - ' the program to stop execution, but unlike clearing a ' - 'breakpoint, it\n' - ' remains in the list of breakpoints and can be (re-)enabled.\n' - '\n' - 'enable [bpnumber ...]\n' - '\n' - ' Enable the breakpoints specified.\n' - '\n' - 'ignore bpnumber [count]\n' - '\n' - ' Set the ignore count for the given breakpoint number. If ' - 'count is\n' - ' omitted, the ignore count is set to 0. A breakpoint becomes ' - 'active\n' - ' when the ignore count is zero. When non-zero, the count is\n' - ' decremented each time the breakpoint is reached and the ' - 'breakpoint\n' - ' is not disabled and any associated condition evaluates to ' - 'true.\n' - '\n' - 'condition bpnumber [condition]\n' - '\n' - ' Set a new *condition* for the breakpoint, an expression which ' - 'must\n' - ' evaluate to true before the breakpoint is honored. If ' - '*condition*\n' - ' is absent, any existing condition is removed; i.e., the ' - 'breakpoint\n' - ' is made unconditional.\n' - '\n' - 'commands [bpnumber]\n' - '\n' - ' Specify a list of commands for breakpoint number *bpnumber*. ' - 'The\n' - ' commands themselves appear on the following lines. Type a ' - 'line\n' - ' containing just "end" to terminate the commands. An example:\n' - '\n' - ' (Pdb) commands 1\n' - ' (com) p some_variable\n' - ' (com) end\n' - ' (Pdb)\n' - '\n' - ' To remove all commands from a breakpoint, type "commands" ' - 'and\n' - ' follow it immediately with "end"; that is, give no commands.\n' - '\n' - ' With no *bpnumber* argument, "commands" refers to the last\n' - ' breakpoint set.\n' - '\n' - ' You can use breakpoint commands to start your program up ' - 'again.\n' - ' Simply use the "continue" command, or "step", or any other ' - 'command\n' - ' that resumes execution.\n' - '\n' - ' Specifying any command resuming execution (currently ' - '"continue",\n' - ' "step", "next", "return", "jump", "quit" and their ' - 'abbreviations)\n' - ' terminates the command list (as if that command was ' - 'immediately\n' - ' followed by end). This is because any time you resume ' - 'execution\n' - ' (even with a simple next or step), you may encounter another\n' - ' breakpoint—which could have its own command list, leading to\n' - ' ambiguities about which list to execute.\n' - '\n' - ' If you use the ‘silent’ command in the command list, the ' - 'usual\n' - ' message about stopping at a breakpoint is not printed. This ' - 'may be\n' - ' desirable for breakpoints that are to print a specific ' - 'message and\n' - ' then continue. If none of the other commands print anything, ' - 'you\n' - ' see no sign that the breakpoint was reached.\n' - '\n' - 's(tep)\n' - '\n' - ' Execute the current line, stop at the first possible ' - 'occasion\n' - ' (either in a function that is called or on the next line in ' - 'the\n' - ' current function).\n' - '\n' - 'n(ext)\n' - '\n' - ' Continue execution until the next line in the current ' - 'function is\n' - ' reached or it returns. (The difference between "next" and ' - '"step"\n' - ' is that "step" stops inside a called function, while "next"\n' - ' executes called functions at (nearly) full speed, only ' - 'stopping at\n' - ' the next line in the current function.)\n' - '\n' - 'unt(il) [lineno]\n' - '\n' - ' Without argument, continue execution until the line with a ' - 'number\n' - ' greater than the current one is reached.\n' - '\n' - ' With a line number, continue execution until a line with a ' - 'number\n' - ' greater or equal to that is reached. In both cases, also ' - 'stop when\n' - ' the current frame returns.\n' - '\n' - ' Changed in version 3.2: Allow giving an explicit line ' - 'number.\n' - '\n' - 'r(eturn)\n' - '\n' - ' Continue execution until the current function returns.\n' - '\n' - 'c(ont(inue))\n' - '\n' - ' Continue execution, only stop when a breakpoint is ' - 'encountered.\n' - '\n' - 'j(ump) lineno\n' - '\n' - ' Set the next line that will be executed. Only available in ' - 'the\n' - ' bottom-most frame. This lets you jump back and execute code ' - 'again,\n' - ' or jump forward to skip code that you don’t want to run.\n' - '\n' - ' It should be noted that not all jumps are allowed – for ' - 'instance it\n' - ' is not possible to jump into the middle of a "for" loop or ' - 'out of a\n' - ' "finally" clause.\n' - '\n' - 'l(ist) [first[, last]]\n' - '\n' - ' List source code for the current file. Without arguments, ' - 'list 11\n' - ' lines around the current line or continue the previous ' - 'listing.\n' - ' With "." as argument, list 11 lines around the current line. ' - 'With\n' - ' one argument, list 11 lines around at that line. With two\n' - ' arguments, list the given range; if the second argument is ' - 'less\n' - ' than the first, it is interpreted as a count.\n' - '\n' - ' The current line in the current frame is indicated by "->". ' - 'If an\n' - ' exception is being debugged, the line where the exception ' - 'was\n' - ' originally raised or propagated is indicated by ">>", if it ' - 'differs\n' - ' from the current line.\n' - '\n' - ' New in version 3.2: The ">>" marker.\n' - '\n' - 'll | longlist\n' - '\n' - ' List all source code for the current function or frame.\n' - ' Interesting lines are marked as for "list".\n' - '\n' - ' New in version 3.2.\n' - '\n' - 'a(rgs)\n' - '\n' - ' Print the argument list of the current function.\n' - '\n' - 'p expression\n' - '\n' - ' Evaluate the *expression* in the current context and print ' - 'its\n' - ' value.\n' - '\n' - ' Note:\n' - '\n' - ' "print()" can also be used, but is not a debugger command — ' - 'this\n' - ' executes the Python "print()" function.\n' - '\n' - 'pp expression\n' - '\n' - ' Like the "p" command, except the value of the expression is ' - 'pretty-\n' - ' printed using the "pprint" module.\n' - '\n' - 'whatis expression\n' - '\n' - ' Print the type of the *expression*.\n' - '\n' - 'source expression\n' - '\n' - ' Try to get source code for the given object and display it.\n' - '\n' - ' New in version 3.2.\n' - '\n' - 'display [expression]\n' - '\n' - ' Display the value of the expression if it changed, each time\n' - ' execution stops in the current frame.\n' - '\n' - ' Without expression, list all display expressions for the ' - 'current\n' - ' frame.\n' - '\n' - ' New in version 3.2.\n' - '\n' - 'undisplay [expression]\n' - '\n' - ' Do not display the expression any more in the current frame.\n' - ' Without expression, clear all display expressions for the ' - 'current\n' - ' frame.\n' - '\n' - ' New in version 3.2.\n' - '\n' - 'interact\n' - '\n' - ' Start an interactive interpreter (using the "code" module) ' - 'whose\n' - ' global namespace contains all the (global and local) names ' - 'found in\n' - ' the current scope.\n' - '\n' - ' New in version 3.2.\n' - '\n' - 'alias [name [command]]\n' - '\n' - ' Create an alias called *name* that executes *command*. The ' - 'command\n' - ' must *not* be enclosed in quotes. Replaceable parameters can ' - 'be\n' - ' indicated by "%1", "%2", and so on, while "%*" is replaced by ' - 'all\n' - ' the parameters. If no command is given, the current alias ' - 'for\n' - ' *name* is shown. If no arguments are given, all aliases are ' - 'listed.\n' - '\n' - ' Aliases may be nested and can contain anything that can be ' - 'legally\n' - ' typed at the pdb prompt. Note that internal pdb commands ' - '*can* be\n' - ' overridden by aliases. Such a command is then hidden until ' - 'the\n' - ' alias is removed. Aliasing is recursively applied to the ' - 'first\n' - ' word of the command line; all other words in the line are ' - 'left\n' - ' alone.\n' - '\n' - ' As an example, here are two useful aliases (especially when ' - 'placed\n' - ' in the ".pdbrc" file):\n' - '\n' - ' # Print instance variables (usage "pi classInst")\n' - ' alias pi for k in %1.__dict__.keys(): ' - 'print("%1.",k,"=",%1.__dict__[k])\n' - ' # Print instance variables in self\n' - ' alias ps pi self\n' - '\n' - 'unalias name\n' - '\n' - ' Delete the specified alias.\n' - '\n' - '! statement\n' - '\n' - ' Execute the (one-line) *statement* in the context of the ' - 'current\n' - ' stack frame. The exclamation point can be omitted unless the ' - 'first\n' - ' word of the statement resembles a debugger command. To set ' - 'a\n' - ' global variable, you can prefix the assignment command with ' - 'a\n' - ' "global" statement on the same line, e.g.:\n' - '\n' - " (Pdb) global list_options; list_options = ['-l']\n" - ' (Pdb)\n' - '\n' - 'run [args ...]\n' - 'restart [args ...]\n' - '\n' - ' Restart the debugged Python program. If an argument is ' - 'supplied,\n' - ' it is split with "shlex" and the result is used as the new\n' - ' "sys.argv". History, breakpoints, actions and debugger ' - 'options are\n' - ' preserved. "restart" is an alias for "run".\n' - '\n' - 'q(uit)\n' - '\n' - ' Quit from the debugger. The program being executed is ' - 'aborted.\n' - '\n' - 'debug code\n' - '\n' - ' Enter a recursive debugger that steps through the code ' - 'argument\n' - ' (which is an arbitrary expression or statement to be executed ' - 'in\n' - ' the current environment).\n' - '\n' - 'retval\n' - '\n' - ' Print the return value for the last return of a function.\n' - '\n' - '-[ Footnotes ]-\n' - '\n' - '[1] Whether a frame is considered to originate in a certain ' - 'module is\n' - ' determined by the "__name__" in the frame globals.\n', - 'del': 'The "del" statement\n' - '*******************\n' - '\n' - ' del_stmt ::= "del" target_list\n' - '\n' - 'Deletion is recursively defined very similar to the way assignment ' - 'is\n' - 'defined. Rather than spelling it out in full details, here are some\n' - 'hints.\n' - '\n' - 'Deletion of a target list recursively deletes each target, from left\n' - 'to right.\n' - '\n' - 'Deletion of a name removes the binding of that name from the local ' - 'or\n' - 'global namespace, depending on whether the name occurs in a "global"\n' - 'statement in the same code block. If the name is unbound, a\n' - '"NameError" exception will be raised.\n' - '\n' - 'Deletion of attribute references, subscriptions and slicings is ' - 'passed\n' - 'to the primary object involved; deletion of a slicing is in general\n' - 'equivalent to assignment of an empty slice of the right type (but ' - 'even\n' - 'this is determined by the sliced object).\n' - '\n' - 'Changed in version 3.2: Previously it was illegal to delete a name\n' - 'from the local namespace if it occurs as a free variable in a nested\n' - 'block.\n', - 'dict': 'Dictionary displays\n' - '*******************\n' - '\n' - 'A dictionary display is a possibly empty series of key/datum pairs\n' - 'enclosed in curly braces:\n' - '\n' - ' dict_display ::= "{" [key_datum_list | dict_comprehension] ' - '"}"\n' - ' key_datum_list ::= key_datum ("," key_datum)* [","]\n' - ' key_datum ::= expression ":" expression | "**" or_expr\n' - ' dict_comprehension ::= expression ":" expression comp_for\n' - '\n' - 'A dictionary display yields a new dictionary object.\n' - '\n' - 'If a comma-separated sequence of key/datum pairs is given, they are\n' - 'evaluated from left to right to define the entries of the ' - 'dictionary:\n' - 'each key object is used as a key into the dictionary to store the\n' - 'corresponding datum. This means that you can specify the same key\n' - 'multiple times in the key/datum list, and the final dictionary’s ' - 'value\n' - 'for that key will be the last one given.\n' - '\n' - 'A double asterisk "**" denotes *dictionary unpacking*. Its operand\n' - 'must be a *mapping*. Each mapping item is added to the new\n' - 'dictionary. Later values replace values already set by earlier\n' - 'key/datum pairs and earlier dictionary unpackings.\n' - '\n' - 'New in version 3.5: Unpacking into dictionary displays, originally\n' - 'proposed by **PEP 448**.\n' - '\n' - 'A dict comprehension, in contrast to list and set comprehensions,\n' - 'needs two expressions separated with a colon followed by the usual\n' - '“for” and “if” clauses. When the comprehension is run, the ' - 'resulting\n' - 'key and value elements are inserted in the new dictionary in the ' - 'order\n' - 'they are produced.\n' - '\n' - 'Restrictions on the types of the key values are listed earlier in\n' - 'section The standard type hierarchy. (To summarize, the key type\n' - 'should be *hashable*, which excludes all mutable objects.) Clashes\n' - 'between duplicate keys are not detected; the last datum (textually\n' - 'rightmost in the display) stored for a given key value prevails.\n' - '\n' - 'Changed in version 3.8: Prior to Python 3.8, in dict ' - 'comprehensions,\n' - 'the evaluation order of key and value was not well-defined. In\n' - 'CPython, the value was evaluated before the key. Starting with ' - '3.8,\n' - 'the key is evaluated before the value, as proposed by **PEP 572**.\n', - 'dynamic-features': 'Interaction with dynamic features\n' - '*********************************\n' - '\n' - 'Name resolution of free variables occurs at runtime, not ' - 'at compile\n' - 'time. This means that the following code will print 42:\n' - '\n' - ' i = 10\n' - ' def f():\n' - ' print(i)\n' - ' i = 42\n' - ' f()\n' - '\n' - 'The "eval()" and "exec()" functions do not have access ' - 'to the full\n' - 'environment for resolving names. Names may be resolved ' - 'in the local\n' - 'and global namespaces of the caller. Free variables are ' - 'not resolved\n' - 'in the nearest enclosing namespace, but in the global ' - 'namespace. [1]\n' - 'The "exec()" and "eval()" functions have optional ' - 'arguments to\n' - 'override the global and local namespace. If only one ' - 'namespace is\n' - 'specified, it is used for both.\n', - 'else': 'The "if" statement\n' - '******************\n' - '\n' - 'The "if" statement is used for conditional execution:\n' - '\n' - ' if_stmt ::= "if" assignment_expression ":" suite\n' - ' ("elif" assignment_expression ":" suite)*\n' - ' ["else" ":" suite]\n' - '\n' - 'It selects exactly one of the suites by evaluating the expressions ' - 'one\n' - 'by one until one is found to be true (see section Boolean ' - 'operations\n' - 'for the definition of true and false); then that suite is executed\n' - '(and no other part of the "if" statement is executed or evaluated).\n' - 'If all expressions are false, the suite of the "else" clause, if\n' - 'present, is executed.\n', - 'exceptions': 'Exceptions\n' - '**********\n' - '\n' - 'Exceptions are a means of breaking out of the normal flow of ' - 'control\n' - 'of a code block in order to handle errors or other ' - 'exceptional\n' - 'conditions. An exception is *raised* at the point where the ' - 'error is\n' - 'detected; it may be *handled* by the surrounding code block or ' - 'by any\n' - 'code block that directly or indirectly invoked the code block ' - 'where\n' - 'the error occurred.\n' - '\n' - 'The Python interpreter raises an exception when it detects a ' - 'run-time\n' - 'error (such as division by zero). A Python program can also\n' - 'explicitly raise an exception with the "raise" statement. ' - 'Exception\n' - 'handlers are specified with the "try" … "except" statement. ' - 'The\n' - '"finally" clause of such a statement can be used to specify ' - 'cleanup\n' - 'code which does not handle the exception, but is executed ' - 'whether an\n' - 'exception occurred or not in the preceding code.\n' - '\n' - 'Python uses the “termination” model of error handling: an ' - 'exception\n' - 'handler can find out what happened and continue execution at ' - 'an outer\n' - 'level, but it cannot repair the cause of the error and retry ' - 'the\n' - 'failing operation (except by re-entering the offending piece ' - 'of code\n' - 'from the top).\n' - '\n' - 'When an exception is not handled at all, the interpreter ' - 'terminates\n' - 'execution of the program, or returns to its interactive main ' - 'loop. In\n' - 'either case, it prints a stack traceback, except when the ' - 'exception is\n' - '"SystemExit".\n' - '\n' - 'Exceptions are identified by class instances. The "except" ' - 'clause is\n' - 'selected depending on the class of the instance: it must ' - 'reference the\n' - 'class of the instance or a *non-virtual base class* thereof. ' - 'The\n' - 'instance can be received by the handler and can carry ' - 'additional\n' - 'information about the exceptional condition.\n' - '\n' - 'Note:\n' - '\n' - ' Exception messages are not part of the Python API. Their ' - 'contents\n' - ' may change from one version of Python to the next without ' - 'warning\n' - ' and should not be relied on by code which will run under ' - 'multiple\n' - ' versions of the interpreter.\n' - '\n' - 'See also the description of the "try" statement in section The ' - 'try\n' - 'statement and "raise" statement in section The raise ' - 'statement.\n' - '\n' - '-[ Footnotes ]-\n' - '\n' - '[1] This limitation occurs because the code that is executed ' - 'by these\n' - ' operations is not available at the time the module is ' - 'compiled.\n', - 'execmodel': 'Execution model\n' - '***************\n' - '\n' - '\n' - 'Structure of a program\n' - '======================\n' - '\n' - 'A Python program is constructed from code blocks. A *block* is ' - 'a piece\n' - 'of Python program text that is executed as a unit. The ' - 'following are\n' - 'blocks: a module, a function body, and a class definition. ' - 'Each\n' - 'command typed interactively is a block. A script file (a file ' - 'given\n' - 'as standard input to the interpreter or specified as a command ' - 'line\n' - 'argument to the interpreter) is a code block. A script command ' - '(a\n' - 'command specified on the interpreter command line with the ' - '"-c"\n' - 'option) is a code block. A module run as a top level script (as ' - 'module\n' - '"__main__") from the command line using a "-m" argument is also ' - 'a code\n' - 'block. The string argument passed to the built-in functions ' - '"eval()"\n' - 'and "exec()" is a code block.\n' - '\n' - 'A code block is executed in an *execution frame*. A frame ' - 'contains\n' - 'some administrative information (used for debugging) and ' - 'determines\n' - 'where and how execution continues after the code block’s ' - 'execution has\n' - 'completed.\n' - '\n' - '\n' - 'Naming and binding\n' - '==================\n' - '\n' - '\n' - 'Binding of names\n' - '----------------\n' - '\n' - '*Names* refer to objects. Names are introduced by name ' - 'binding\n' - 'operations.\n' - '\n' - 'The following constructs bind names:\n' - '\n' - '* formal parameters to functions,\n' - '\n' - '* class definitions,\n' - '\n' - '* function definitions,\n' - '\n' - '* assignment expressions,\n' - '\n' - '* targets that are identifiers if occurring in an assignment:\n' - '\n' - ' * "for" loop header,\n' - '\n' - ' * after "as" in a "with" statement, "except" clause or in the ' - 'as-\n' - ' pattern in structural pattern matching,\n' - '\n' - ' * in a capture pattern in structural pattern matching\n' - '\n' - '* "import" statements.\n' - '\n' - 'The "import" statement of the form "from ... import *" binds ' - 'all names\n' - 'defined in the imported module, except those beginning with an\n' - 'underscore. This form may only be used at the module level.\n' - '\n' - 'A target occurring in a "del" statement is also considered ' - 'bound for\n' - 'this purpose (though the actual semantics are to unbind the ' - 'name).\n' - '\n' - 'Each assignment or import statement occurs within a block ' - 'defined by a\n' - 'class or function definition or at the module level (the ' - 'top-level\n' - 'code block).\n' - '\n' - 'If a name is bound in a block, it is a local variable of that ' - 'block,\n' - 'unless declared as "nonlocal" or "global". If a name is bound ' - 'at the\n' - 'module level, it is a global variable. (The variables of the ' - 'module\n' - 'code block are local and global.) If a variable is used in a ' - 'code\n' - 'block but not defined there, it is a *free variable*.\n' - '\n' - 'Each occurrence of a name in the program text refers to the ' - '*binding*\n' - 'of that name established by the following name resolution ' - 'rules.\n' - '\n' - '\n' - 'Resolution of names\n' - '-------------------\n' - '\n' - 'A *scope* defines the visibility of a name within a block. If ' - 'a local\n' - 'variable is defined in a block, its scope includes that block. ' - 'If the\n' - 'definition occurs in a function block, the scope extends to any ' - 'blocks\n' - 'contained within the defining one, unless a contained block ' - 'introduces\n' - 'a different binding for the name.\n' - '\n' - 'When a name is used in a code block, it is resolved using the ' - 'nearest\n' - 'enclosing scope. The set of all such scopes visible to a code ' - 'block\n' - 'is called the block’s *environment*.\n' - '\n' - 'When a name is not found at all, a "NameError" exception is ' - 'raised. If\n' - 'the current scope is a function scope, and the name refers to a ' - 'local\n' - 'variable that has not yet been bound to a value at the point ' - 'where the\n' - 'name is used, an "UnboundLocalError" exception is raised.\n' - '"UnboundLocalError" is a subclass of "NameError".\n' - '\n' - 'If a name binding operation occurs anywhere within a code ' - 'block, all\n' - 'uses of the name within the block are treated as references to ' - 'the\n' - 'current block. This can lead to errors when a name is used ' - 'within a\n' - 'block before it is bound. This rule is subtle. Python lacks\n' - 'declarations and allows name binding operations to occur ' - 'anywhere\n' - 'within a code block. The local variables of a code block can ' - 'be\n' - 'determined by scanning the entire text of the block for name ' - 'binding\n' - 'operations.\n' - '\n' - 'If the "global" statement occurs within a block, all uses of ' - 'the names\n' - 'specified in the statement refer to the bindings of those names ' - 'in the\n' - 'top-level namespace. Names are resolved in the top-level ' - 'namespace by\n' - 'searching the global namespace, i.e. the namespace of the ' - 'module\n' - 'containing the code block, and the builtins namespace, the ' - 'namespace\n' - 'of the module "builtins". The global namespace is searched ' - 'first. If\n' - 'the names are not found there, the builtins namespace is ' - 'searched.\n' - 'The "global" statement must precede all uses of the listed ' - 'names.\n' - '\n' - 'The "global" statement has the same scope as a name binding ' - 'operation\n' - 'in the same block. If the nearest enclosing scope for a free ' - 'variable\n' - 'contains a global statement, the free variable is treated as a ' - 'global.\n' - '\n' - 'The "nonlocal" statement causes corresponding names to refer ' - 'to\n' - 'previously bound variables in the nearest enclosing function ' - 'scope.\n' - '"SyntaxError" is raised at compile time if the given name does ' - 'not\n' - 'exist in any enclosing function scope.\n' - '\n' - 'The namespace for a module is automatically created the first ' - 'time a\n' - 'module is imported. The main module for a script is always ' - 'called\n' - '"__main__".\n' - '\n' - 'Class definition blocks and arguments to "exec()" and "eval()" ' - 'are\n' - 'special in the context of name resolution. A class definition ' - 'is an\n' - 'executable statement that may use and define names. These ' - 'references\n' - 'follow the normal rules for name resolution with an exception ' - 'that\n' - 'unbound local variables are looked up in the global namespace. ' - 'The\n' - 'namespace of the class definition becomes the attribute ' - 'dictionary of\n' - 'the class. The scope of names defined in a class block is ' - 'limited to\n' - 'the class block; it does not extend to the code blocks of ' - 'methods –\n' - 'this includes comprehensions and generator expressions since ' - 'they are\n' - 'implemented using a function scope. This means that the ' - 'following\n' - 'will fail:\n' - '\n' - ' class A:\n' - ' a = 42\n' - ' b = list(a + i for i in range(10))\n' - '\n' - '\n' - 'Builtins and restricted execution\n' - '---------------------------------\n' - '\n' - '**CPython implementation detail:** Users should not touch\n' - '"__builtins__"; it is strictly an implementation detail. ' - 'Users\n' - 'wanting to override values in the builtins namespace should ' - '"import"\n' - 'the "builtins" module and modify its attributes appropriately.\n' - '\n' - 'The builtins namespace associated with the execution of a code ' - 'block\n' - 'is actually found by looking up the name "__builtins__" in its ' - 'global\n' - 'namespace; this should be a dictionary or a module (in the ' - 'latter case\n' - 'the module’s dictionary is used). By default, when in the ' - '"__main__"\n' - 'module, "__builtins__" is the built-in module "builtins"; when ' - 'in any\n' - 'other module, "__builtins__" is an alias for the dictionary of ' - 'the\n' - '"builtins" module itself.\n' - '\n' - '\n' - 'Interaction with dynamic features\n' - '---------------------------------\n' - '\n' - 'Name resolution of free variables occurs at runtime, not at ' - 'compile\n' - 'time. This means that the following code will print 42:\n' - '\n' - ' i = 10\n' - ' def f():\n' - ' print(i)\n' - ' i = 42\n' - ' f()\n' - '\n' - 'The "eval()" and "exec()" functions do not have access to the ' - 'full\n' - 'environment for resolving names. Names may be resolved in the ' - 'local\n' - 'and global namespaces of the caller. Free variables are not ' - 'resolved\n' - 'in the nearest enclosing namespace, but in the global ' - 'namespace. [1]\n' - 'The "exec()" and "eval()" functions have optional arguments to\n' - 'override the global and local namespace. If only one namespace ' - 'is\n' - 'specified, it is used for both.\n' - '\n' - '\n' - 'Exceptions\n' - '==========\n' - '\n' - 'Exceptions are a means of breaking out of the normal flow of ' - 'control\n' - 'of a code block in order to handle errors or other exceptional\n' - 'conditions. An exception is *raised* at the point where the ' - 'error is\n' - 'detected; it may be *handled* by the surrounding code block or ' - 'by any\n' - 'code block that directly or indirectly invoked the code block ' - 'where\n' - 'the error occurred.\n' - '\n' - 'The Python interpreter raises an exception when it detects a ' - 'run-time\n' - 'error (such as division by zero). A Python program can also\n' - 'explicitly raise an exception with the "raise" statement. ' - 'Exception\n' - 'handlers are specified with the "try" … "except" statement. ' - 'The\n' - '"finally" clause of such a statement can be used to specify ' - 'cleanup\n' - 'code which does not handle the exception, but is executed ' - 'whether an\n' - 'exception occurred or not in the preceding code.\n' - '\n' - 'Python uses the “termination” model of error handling: an ' - 'exception\n' - 'handler can find out what happened and continue execution at an ' - 'outer\n' - 'level, but it cannot repair the cause of the error and retry ' - 'the\n' - 'failing operation (except by re-entering the offending piece of ' - 'code\n' - 'from the top).\n' - '\n' - 'When an exception is not handled at all, the interpreter ' - 'terminates\n' - 'execution of the program, or returns to its interactive main ' - 'loop. In\n' - 'either case, it prints a stack traceback, except when the ' - 'exception is\n' - '"SystemExit".\n' - '\n' - 'Exceptions are identified by class instances. The "except" ' - 'clause is\n' - 'selected depending on the class of the instance: it must ' - 'reference the\n' - 'class of the instance or a *non-virtual base class* thereof. ' - 'The\n' - 'instance can be received by the handler and can carry ' - 'additional\n' - 'information about the exceptional condition.\n' - '\n' - 'Note:\n' - '\n' - ' Exception messages are not part of the Python API. Their ' - 'contents\n' - ' may change from one version of Python to the next without ' - 'warning\n' - ' and should not be relied on by code which will run under ' - 'multiple\n' - ' versions of the interpreter.\n' - '\n' - 'See also the description of the "try" statement in section The ' - 'try\n' - 'statement and "raise" statement in section The raise ' - 'statement.\n' - '\n' - '-[ Footnotes ]-\n' - '\n' - '[1] This limitation occurs because the code that is executed by ' - 'these\n' - ' operations is not available at the time the module is ' - 'compiled.\n', - 'exprlists': 'Expression lists\n' - '****************\n' - '\n' - ' expression_list ::= expression ("," expression)* [","]\n' - ' starred_list ::= starred_item ("," starred_item)* ' - '[","]\n' - ' starred_expression ::= expression | (starred_item ",")* ' - '[starred_item]\n' - ' starred_item ::= assignment_expression | "*" or_expr\n' - '\n' - 'Except when part of a list or set display, an expression list\n' - 'containing at least one comma yields a tuple. The length of ' - 'the tuple\n' - 'is the number of expressions in the list. The expressions are\n' - 'evaluated from left to right.\n' - '\n' - 'An asterisk "*" denotes *iterable unpacking*. Its operand must ' - 'be an\n' - '*iterable*. The iterable is expanded into a sequence of items, ' - 'which\n' - 'are included in the new tuple, list, or set, at the site of ' - 'the\n' - 'unpacking.\n' - '\n' - 'New in version 3.5: Iterable unpacking in expression lists, ' - 'originally\n' - 'proposed by **PEP 448**.\n' - '\n' - 'The trailing comma is required only to create a single tuple ' - '(a.k.a. a\n' - '*singleton*); it is optional in all other cases. A single ' - 'expression\n' - 'without a trailing comma doesn’t create a tuple, but rather ' - 'yields the\n' - 'value of that expression. (To create an empty tuple, use an ' - 'empty pair\n' - 'of parentheses: "()".)\n', - 'floating': 'Floating point literals\n' - '***********************\n' - '\n' - 'Floating point literals are described by the following lexical\n' - 'definitions:\n' - '\n' - ' floatnumber ::= pointfloat | exponentfloat\n' - ' pointfloat ::= [digitpart] fraction | digitpart "."\n' - ' exponentfloat ::= (digitpart | pointfloat) exponent\n' - ' digitpart ::= digit (["_"] digit)*\n' - ' fraction ::= "." digitpart\n' - ' exponent ::= ("e" | "E") ["+" | "-"] digitpart\n' - '\n' - 'Note that the integer and exponent parts are always interpreted ' - 'using\n' - 'radix 10. For example, "077e010" is legal, and denotes the same ' - 'number\n' - 'as "77e10". The allowed range of floating point literals is\n' - 'implementation-dependent. As in integer literals, underscores ' - 'are\n' - 'supported for digit grouping.\n' - '\n' - 'Some examples of floating point literals:\n' - '\n' - ' 3.14 10. .001 1e100 3.14e-10 0e0 ' - '3.14_15_93\n' - '\n' - 'Changed in version 3.6: Underscores are now allowed for ' - 'grouping\n' - 'purposes in literals.\n', - 'for': 'The "for" statement\n' - '*******************\n' - '\n' - 'The "for" statement is used to iterate over the elements of a ' - 'sequence\n' - '(such as a string, tuple or list) or other iterable object:\n' - '\n' - ' for_stmt ::= "for" target_list "in" expression_list ":" suite\n' - ' ["else" ":" suite]\n' - '\n' - 'The expression list is evaluated once; it should yield an iterable\n' - 'object. An iterator is created for the result of the\n' - '"expression_list". The suite is then executed once for each item\n' - 'provided by the iterator, in the order returned by the iterator. ' - 'Each\n' - 'item in turn is assigned to the target list using the standard rules\n' - 'for assignments (see Assignment statements), and then the suite is\n' - 'executed. When the items are exhausted (which is immediately when ' - 'the\n' - 'sequence is empty or an iterator raises a "StopIteration" ' - 'exception),\n' - 'the suite in the "else" clause, if present, is executed, and the ' - 'loop\n' - 'terminates.\n' - '\n' - 'A "break" statement executed in the first suite terminates the loop\n' - 'without executing the "else" clause’s suite. A "continue" statement\n' - 'executed in the first suite skips the rest of the suite and ' - 'continues\n' - 'with the next item, or with the "else" clause if there is no next\n' - 'item.\n' - '\n' - 'The for-loop makes assignments to the variables in the target list.\n' - 'This overwrites all previous assignments to those variables ' - 'including\n' - 'those made in the suite of the for-loop:\n' - '\n' - ' for i in range(10):\n' - ' print(i)\n' - ' i = 5 # this will not affect the for-loop\n' - ' # because i will be overwritten with the ' - 'next\n' - ' # index in the range\n' - '\n' - 'Names in the target list are not deleted when the loop is finished,\n' - 'but if the sequence is empty, they will not have been assigned to at\n' - 'all by the loop. Hint: the built-in function "range()" returns an\n' - 'iterator of integers suitable to emulate the effect of Pascal’s "for ' - 'i\n' - ':= a to b do"; e.g., "list(range(3))" returns the list "[0, 1, 2]".\n', - 'formatstrings': 'Format String Syntax\n' - '********************\n' - '\n' - 'The "str.format()" method and the "Formatter" class share ' - 'the same\n' - 'syntax for format strings (although in the case of ' - '"Formatter",\n' - 'subclasses can define their own format string syntax). The ' - 'syntax is\n' - 'related to that of formatted string literals, but it is ' - 'less\n' - 'sophisticated and, in particular, does not support ' - 'arbitrary\n' - 'expressions.\n' - '\n' - 'Format strings contain “replacement fields” surrounded by ' - 'curly braces\n' - '"{}". Anything that is not contained in braces is ' - 'considered literal\n' - 'text, which is copied unchanged to the output. If you need ' - 'to include\n' - 'a brace character in the literal text, it can be escaped by ' - 'doubling:\n' - '"{{" and "}}".\n' - '\n' - 'The grammar for a replacement field is as follows:\n' - '\n' - ' replacement_field ::= "{" [field_name] ["!" ' - 'conversion] [":" format_spec] "}"\n' - ' field_name ::= arg_name ("." attribute_name | ' - '"[" element_index "]")*\n' - ' arg_name ::= [identifier | digit+]\n' - ' attribute_name ::= identifier\n' - ' element_index ::= digit+ | index_string\n' - ' index_string ::= <any source character except ' - '"]"> +\n' - ' conversion ::= "r" | "s" | "a"\n' - ' format_spec ::= <described in the next ' - 'section>\n' - '\n' - 'In less formal terms, the replacement field can start with ' - 'a\n' - '*field_name* that specifies the object whose value is to be ' - 'formatted\n' - 'and inserted into the output instead of the replacement ' - 'field. The\n' - '*field_name* is optionally followed by a *conversion* ' - 'field, which is\n' - 'preceded by an exclamation point "\'!\'", and a ' - '*format_spec*, which is\n' - 'preceded by a colon "\':\'". These specify a non-default ' - 'format for the\n' - 'replacement value.\n' - '\n' - 'See also the Format Specification Mini-Language section.\n' - '\n' - 'The *field_name* itself begins with an *arg_name* that is ' - 'either a\n' - 'number or a keyword. If it’s a number, it refers to a ' - 'positional\n' - 'argument, and if it’s a keyword, it refers to a named ' - 'keyword\n' - 'argument. If the numerical arg_names in a format string ' - 'are 0, 1, 2,\n' - '… in sequence, they can all be omitted (not just some) and ' - 'the numbers\n' - '0, 1, 2, … will be automatically inserted in that order. ' - 'Because\n' - '*arg_name* is not quote-delimited, it is not possible to ' - 'specify\n' - 'arbitrary dictionary keys (e.g., the strings "\'10\'" or ' - '"\':-]\'") within\n' - 'a format string. The *arg_name* can be followed by any ' - 'number of index\n' - 'or attribute expressions. An expression of the form ' - '"\'.name\'" selects\n' - 'the named attribute using "getattr()", while an expression ' - 'of the form\n' - '"\'[index]\'" does an index lookup using "__getitem__()".\n' - '\n' - 'Changed in version 3.1: The positional argument specifiers ' - 'can be\n' - 'omitted for "str.format()", so "\'{} {}\'.format(a, b)" is ' - 'equivalent to\n' - '"\'{0} {1}\'.format(a, b)".\n' - '\n' - 'Changed in version 3.4: The positional argument specifiers ' - 'can be\n' - 'omitted for "Formatter".\n' - '\n' - 'Some simple format string examples:\n' - '\n' - ' "First, thou shalt count to {0}" # References first ' - 'positional argument\n' - ' "Bring me a {}" # Implicitly ' - 'references the first positional argument\n' - ' "From {} to {}" # Same as "From {0} to ' - '{1}"\n' - ' "My quest is {name}" # References keyword ' - "argument 'name'\n" - ' "Weight in tons {0.weight}" # \'weight\' attribute ' - 'of first positional arg\n' - ' "Units destroyed: {players[0]}" # First element of ' - "keyword argument 'players'.\n" - '\n' - 'The *conversion* field causes a type coercion before ' - 'formatting.\n' - 'Normally, the job of formatting a value is done by the ' - '"__format__()"\n' - 'method of the value itself. However, in some cases it is ' - 'desirable to\n' - 'force a type to be formatted as a string, overriding its ' - 'own\n' - 'definition of formatting. By converting the value to a ' - 'string before\n' - 'calling "__format__()", the normal formatting logic is ' - 'bypassed.\n' - '\n' - 'Three conversion flags are currently supported: "\'!s\'" ' - 'which calls\n' - '"str()" on the value, "\'!r\'" which calls "repr()" and ' - '"\'!a\'" which\n' - 'calls "ascii()".\n' - '\n' - 'Some examples:\n' - '\n' - ' "Harold\'s a clever {0!s}" # Calls str() on the ' - 'argument first\n' - ' "Bring out the holy {name!r}" # Calls repr() on the ' - 'argument first\n' - ' "More {!a}" # Calls ascii() on the ' - 'argument first\n' - '\n' - 'The *format_spec* field contains a specification of how the ' - 'value\n' - 'should be presented, including such details as field width, ' - 'alignment,\n' - 'padding, decimal precision and so on. Each value type can ' - 'define its\n' - 'own “formatting mini-language” or interpretation of the ' - '*format_spec*.\n' - '\n' - 'Most built-in types support a common formatting ' - 'mini-language, which\n' - 'is described in the next section.\n' - '\n' - 'A *format_spec* field can also include nested replacement ' - 'fields\n' - 'within it. These nested replacement fields may contain a ' - 'field name,\n' - 'conversion flag and format specification, but deeper ' - 'nesting is not\n' - 'allowed. The replacement fields within the format_spec ' - 'are\n' - 'substituted before the *format_spec* string is interpreted. ' - 'This\n' - 'allows the formatting of a value to be dynamically ' - 'specified.\n' - '\n' - 'See the Format examples section for some examples.\n' - '\n' - '\n' - 'Format Specification Mini-Language\n' - '==================================\n' - '\n' - '“Format specifications” are used within replacement fields ' - 'contained\n' - 'within a format string to define how individual values are ' - 'presented\n' - '(see Format String Syntax and Formatted string literals). ' - 'They can\n' - 'also be passed directly to the built-in "format()" ' - 'function. Each\n' - 'formattable type may define how the format specification is ' - 'to be\n' - 'interpreted.\n' - '\n' - 'Most built-in types implement the following options for ' - 'format\n' - 'specifications, although some of the formatting options are ' - 'only\n' - 'supported by the numeric types.\n' - '\n' - 'A general convention is that an empty format specification ' - 'produces\n' - 'the same result as if you had called "str()" on the value. ' - 'A non-empty\n' - 'format specification typically modifies the result.\n' - '\n' - 'The general form of a *standard format specifier* is:\n' - '\n' - ' format_spec ::= ' - '[[fill]align][sign][#][0][width][grouping_option][.precision][type]\n' - ' fill ::= <any character>\n' - ' align ::= "<" | ">" | "=" | "^"\n' - ' sign ::= "+" | "-" | " "\n' - ' width ::= digit+\n' - ' grouping_option ::= "_" | ","\n' - ' precision ::= digit+\n' - ' type ::= "b" | "c" | "d" | "e" | "E" | "f" | ' - '"F" | "g" | "G" | "n" | "o" | "s" | "x" | "X" | "%"\n' - '\n' - 'If a valid *align* value is specified, it can be preceded ' - 'by a *fill*\n' - 'character that can be any character and defaults to a space ' - 'if\n' - 'omitted. It is not possible to use a literal curly brace ' - '(”"{"” or\n' - '“"}"”) as the *fill* character in a formatted string ' - 'literal or when\n' - 'using the "str.format()" method. However, it is possible ' - 'to insert a\n' - 'curly brace with a nested replacement field. This ' - 'limitation doesn’t\n' - 'affect the "format()" function.\n' - '\n' - 'The meaning of the various alignment options is as ' - 'follows:\n' - '\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - ' | Option | ' - 'Meaning ' - '|\n' - ' ' - '|===========|============================================================|\n' - ' | "\'<\'" | Forces the field to be left-aligned ' - 'within the available |\n' - ' | | space (this is the default for most ' - 'objects). |\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - ' | "\'>\'" | Forces the field to be right-aligned ' - 'within the available |\n' - ' | | space (this is the default for ' - 'numbers). |\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - ' | "\'=\'" | Forces the padding to be placed after ' - 'the sign (if any) |\n' - ' | | but before the digits. This is used for ' - 'printing fields |\n' - ' | | in the form ‘+000000120’. This alignment ' - 'option is only |\n' - ' | | valid for numeric types. It becomes the ' - 'default for |\n' - ' | | numbers when ‘0’ immediately precedes the ' - 'field width. |\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - ' | "\'^\'" | Forces the field to be centered within ' - 'the available |\n' - ' | | ' - 'space. ' - '|\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - '\n' - 'Note that unless a minimum field width is defined, the ' - 'field width\n' - 'will always be the same size as the data to fill it, so ' - 'that the\n' - 'alignment option has no meaning in this case.\n' - '\n' - 'The *sign* option is only valid for number types, and can ' - 'be one of\n' - 'the following:\n' - '\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - ' | Option | ' - 'Meaning ' - '|\n' - ' ' - '|===========|============================================================|\n' - ' | "\'+\'" | indicates that a sign should be used for ' - 'both positive as |\n' - ' | | well as negative ' - 'numbers. |\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - ' | "\'-\'" | indicates that a sign should be used ' - 'only for negative |\n' - ' | | numbers (this is the default ' - 'behavior). |\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - ' | space | indicates that a leading space should be ' - 'used on positive |\n' - ' | | numbers, and a minus sign on negative ' - 'numbers. |\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - '\n' - 'The "\'#\'" option causes the “alternate form” to be used ' - 'for the\n' - 'conversion. The alternate form is defined differently for ' - 'different\n' - 'types. This option is only valid for integer, float and ' - 'complex\n' - 'types. For integers, when binary, octal, or hexadecimal ' - 'output is\n' - 'used, this option adds the respective prefix "\'0b\'", ' - '"\'0o\'", "\'0x\'",\n' - 'or "\'0X\'" to the output value. For float and complex the ' - 'alternate\n' - 'form causes the result of the conversion to always contain ' - 'a decimal-\n' - 'point character, even if no digits follow it. Normally, a ' - 'decimal-\n' - 'point character appears in the result of these conversions ' - 'only if a\n' - 'digit follows it. In addition, for "\'g\'" and "\'G\'" ' - 'conversions,\n' - 'trailing zeros are not removed from the result.\n' - '\n' - 'The "\',\'" option signals the use of a comma for a ' - 'thousands separator.\n' - 'For a locale aware separator, use the "\'n\'" integer ' - 'presentation type\n' - 'instead.\n' - '\n' - 'Changed in version 3.1: Added the "\',\'" option (see also ' - '**PEP 378**).\n' - '\n' - 'The "\'_\'" option signals the use of an underscore for a ' - 'thousands\n' - 'separator for floating point presentation types and for ' - 'integer\n' - 'presentation type "\'d\'". For integer presentation types ' - '"\'b\'", "\'o\'",\n' - '"\'x\'", and "\'X\'", underscores will be inserted every 4 ' - 'digits. For\n' - 'other presentation types, specifying this option is an ' - 'error.\n' - '\n' - 'Changed in version 3.6: Added the "\'_\'" option (see also ' - '**PEP 515**).\n' - '\n' - '*width* is a decimal integer defining the minimum total ' - 'field width,\n' - 'including any prefixes, separators, and other formatting ' - 'characters.\n' - 'If not specified, then the field width will be determined ' - 'by the\n' - 'content.\n' - '\n' - 'When no explicit alignment is given, preceding the *width* ' - 'field by a\n' - 'zero ("\'0\'") character enables sign-aware zero-padding ' - 'for numeric\n' - 'types. This is equivalent to a *fill* character of "\'0\'" ' - 'with an\n' - '*alignment* type of "\'=\'".\n' - '\n' - 'Changed in version 3.10: Preceding the *width* field by ' - '"\'0\'" no\n' - 'longer affects the default alignment for strings.\n' - '\n' - 'The *precision* is a decimal integer indicating how many ' - 'digits should\n' - 'be displayed after the decimal point for presentation types ' - '"\'f\'" and\n' - '"\'F\'", or before and after the decimal point for ' - 'presentation types\n' - '"\'g\'" or "\'G\'". For string presentation types the ' - 'field indicates the\n' - 'maximum field size - in other words, how many characters ' - 'will be used\n' - 'from the field content. The *precision* is not allowed for ' - 'integer\n' - 'presentation types.\n' - '\n' - 'Finally, the *type* determines how the data should be ' - 'presented.\n' - '\n' - 'The available string presentation types are:\n' - '\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - ' | Type | ' - 'Meaning ' - '|\n' - ' ' - '|===========|============================================================|\n' - ' | "\'s\'" | String format. This is the default type ' - 'for strings and |\n' - ' | | may be ' - 'omitted. |\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - ' | None | The same as ' - '"\'s\'". |\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - '\n' - 'The available integer presentation types are:\n' - '\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - ' | Type | ' - 'Meaning ' - '|\n' - ' ' - '|===========|============================================================|\n' - ' | "\'b\'" | Binary format. Outputs the number in ' - 'base 2. |\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - ' | "\'c\'" | Character. Converts the integer to the ' - 'corresponding |\n' - ' | | unicode character before ' - 'printing. |\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - ' | "\'d\'" | Decimal Integer. Outputs the number in ' - 'base 10. |\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - ' | "\'o\'" | Octal format. Outputs the number in base ' - '8. |\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - ' | "\'x\'" | Hex format. Outputs the number in base ' - '16, using lower- |\n' - ' | | case letters for the digits above ' - '9. |\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - ' | "\'X\'" | Hex format. Outputs the number in base ' - '16, using upper- |\n' - ' | | case letters for the digits above 9. In ' - 'case "\'#\'" is |\n' - ' | | specified, the prefix "\'0x\'" will be ' - 'upper-cased to "\'0X\'" |\n' - ' | | as ' - 'well. |\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - ' | "\'n\'" | Number. This is the same as "\'d\'", ' - 'except that it uses the |\n' - ' | | current locale setting to insert the ' - 'appropriate number |\n' - ' | | separator ' - 'characters. |\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - ' | None | The same as ' - '"\'d\'". |\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - '\n' - 'In addition to the above presentation types, integers can ' - 'be formatted\n' - 'with the floating point presentation types listed below ' - '(except "\'n\'"\n' - 'and "None"). When doing so, "float()" is used to convert ' - 'the integer\n' - 'to a floating point number before formatting.\n' - '\n' - 'The available presentation types for "float" and "Decimal" ' - 'values are:\n' - '\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - ' | Type | ' - 'Meaning ' - '|\n' - ' ' - '|===========|============================================================|\n' - ' | "\'e\'" | Scientific notation. For a given ' - 'precision "p", formats |\n' - ' | | the number in scientific notation with the ' - 'letter ‘e’ |\n' - ' | | separating the coefficient from the ' - 'exponent. The |\n' - ' | | coefficient has one digit before and "p" ' - 'digits after the |\n' - ' | | decimal point, for a total of "p + 1" ' - 'significant digits. |\n' - ' | | With no precision given, uses a precision ' - 'of "6" digits |\n' - ' | | after the decimal point for "float", and ' - 'shows all |\n' - ' | | coefficient digits for "Decimal". If no ' - 'digits follow the |\n' - ' | | decimal point, the decimal point is also ' - 'removed unless |\n' - ' | | the "#" option is ' - 'used. |\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - ' | "\'E\'" | Scientific notation. Same as "\'e\'" ' - 'except it uses an upper |\n' - ' | | case ‘E’ as the separator ' - 'character. |\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - ' | "\'f\'" | Fixed-point notation. For a given ' - 'precision "p", formats |\n' - ' | | the number as a decimal number with ' - 'exactly "p" digits |\n' - ' | | following the decimal point. With no ' - 'precision given, uses |\n' - ' | | a precision of "6" digits after the ' - 'decimal point for |\n' - ' | | "float", and uses a precision large enough ' - 'to show all |\n' - ' | | coefficient digits for "Decimal". If no ' - 'digits follow the |\n' - ' | | decimal point, the decimal point is also ' - 'removed unless |\n' - ' | | the "#" option is ' - 'used. |\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - ' | "\'F\'" | Fixed-point notation. Same as "\'f\'", ' - 'but converts "nan" to |\n' - ' | | "NAN" and "inf" to ' - '"INF". |\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - ' | "\'g\'" | General format. For a given precision ' - '"p >= 1", this |\n' - ' | | rounds the number to "p" significant ' - 'digits and then |\n' - ' | | formats the result in either fixed-point ' - 'format or in |\n' - ' | | scientific notation, depending on its ' - 'magnitude. A |\n' - ' | | precision of "0" is treated as equivalent ' - 'to a precision |\n' - ' | | of "1". The precise rules are as follows: ' - 'suppose that |\n' - ' | | the result formatted with presentation ' - 'type "\'e\'" and |\n' - ' | | precision "p-1" would have exponent ' - '"exp". Then, if "m <= |\n' - ' | | exp < p", where "m" is -4 for floats and ' - '-6 for |\n' - ' | | "Decimals", the number is formatted with ' - 'presentation type |\n' - ' | | "\'f\'" and precision "p-1-exp". ' - 'Otherwise, the number is |\n' - ' | | formatted with presentation type "\'e\'" ' - 'and precision |\n' - ' | | "p-1". In both cases insignificant ' - 'trailing zeros are |\n' - ' | | removed from the significand, and the ' - 'decimal point is |\n' - ' | | also removed if there are no remaining ' - 'digits following |\n' - ' | | it, unless the "\'#\'" option is used. ' - 'With no precision |\n' - ' | | given, uses a precision of "6" significant ' - 'digits for |\n' - ' | | "float". For "Decimal", the coefficient of ' - 'the result is |\n' - ' | | formed from the coefficient digits of the ' - 'value; |\n' - ' | | scientific notation is used for values ' - 'smaller than "1e-6" |\n' - ' | | in absolute value and values where the ' - 'place value of the |\n' - ' | | least significant digit is larger than 1, ' - 'and fixed-point |\n' - ' | | notation is used otherwise. Positive and ' - 'negative |\n' - ' | | infinity, positive and negative zero, and ' - 'nans, are |\n' - ' | | formatted as "inf", "-inf", "0", "-0" and ' - '"nan" |\n' - ' | | respectively, regardless of the ' - 'precision. |\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - ' | "\'G\'" | General format. Same as "\'g\'" except ' - 'switches to "\'E\'" if |\n' - ' | | the number gets too large. The ' - 'representations of infinity |\n' - ' | | and NaN are uppercased, ' - 'too. |\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - ' | "\'n\'" | Number. This is the same as "\'g\'", ' - 'except that it uses the |\n' - ' | | current locale setting to insert the ' - 'appropriate number |\n' - ' | | separator ' - 'characters. |\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - ' | "\'%\'" | Percentage. Multiplies the number by 100 ' - 'and displays in |\n' - ' | | fixed ("\'f\'") format, followed by a ' - 'percent sign. |\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - ' | None | For "float" this is the same as "\'g\'", ' - 'except that when |\n' - ' | | fixed-point notation is used to format the ' - 'result, it |\n' - ' | | always includes at least one digit past ' - 'the decimal point. |\n' - ' | | The precision used is as large as needed ' - 'to represent the |\n' - ' | | given value faithfully. For "Decimal", ' - 'this is the same |\n' - ' | | as either "\'g\'" or "\'G\'" depending on ' - 'the value of |\n' - ' | | "context.capitals" for the current decimal ' - 'context. The |\n' - ' | | overall effect is to match the output of ' - '"str()" as |\n' - ' | | altered by the other format ' - 'modifiers. |\n' - ' ' - '+-----------+------------------------------------------------------------+\n' - '\n' - '\n' - 'Format examples\n' - '===============\n' - '\n' - 'This section contains examples of the "str.format()" syntax ' - 'and\n' - 'comparison with the old "%"-formatting.\n' - '\n' - 'In most of the cases the syntax is similar to the old ' - '"%"-formatting,\n' - 'with the addition of the "{}" and with ":" used instead of ' - '"%". For\n' - 'example, "\'%03.2f\'" can be translated to "\'{:03.2f}\'".\n' - '\n' - 'The new format syntax also supports new and different ' - 'options, shown\n' - 'in the following examples.\n' - '\n' - 'Accessing arguments by position:\n' - '\n' - " >>> '{0}, {1}, {2}'.format('a', 'b', 'c')\n" - " 'a, b, c'\n" - " >>> '{}, {}, {}'.format('a', 'b', 'c') # 3.1+ only\n" - " 'a, b, c'\n" - " >>> '{2}, {1}, {0}'.format('a', 'b', 'c')\n" - " 'c, b, a'\n" - " >>> '{2}, {1}, {0}'.format(*'abc') # unpacking " - 'argument sequence\n' - " 'c, b, a'\n" - " >>> '{0}{1}{0}'.format('abra', 'cad') # arguments' " - 'indices can be repeated\n' - " 'abracadabra'\n" - '\n' - 'Accessing arguments by name:\n' - '\n' - " >>> 'Coordinates: {latitude}, " - "{longitude}'.format(latitude='37.24N', " - "longitude='-115.81W')\n" - " 'Coordinates: 37.24N, -115.81W'\n" - " >>> coord = {'latitude': '37.24N', 'longitude': " - "'-115.81W'}\n" - " >>> 'Coordinates: {latitude}, " - "{longitude}'.format(**coord)\n" - " 'Coordinates: 37.24N, -115.81W'\n" - '\n' - 'Accessing arguments’ attributes:\n' - '\n' - ' >>> c = 3-5j\n' - " >>> ('The complex number {0} is formed from the real " - "part {0.real} '\n" - " ... 'and the imaginary part {0.imag}.').format(c)\n" - " 'The complex number (3-5j) is formed from the real part " - "3.0 and the imaginary part -5.0.'\n" - ' >>> class Point:\n' - ' ... def __init__(self, x, y):\n' - ' ... self.x, self.y = x, y\n' - ' ... def __str__(self):\n' - " ... return 'Point({self.x}, " - "{self.y})'.format(self=self)\n" - ' ...\n' - ' >>> str(Point(4, 2))\n' - " 'Point(4, 2)'\n" - '\n' - 'Accessing arguments’ items:\n' - '\n' - ' >>> coord = (3, 5)\n' - " >>> 'X: {0[0]}; Y: {0[1]}'.format(coord)\n" - " 'X: 3; Y: 5'\n" - '\n' - 'Replacing "%s" and "%r":\n' - '\n' - ' >>> "repr() shows quotes: {!r}; str() doesn\'t: ' - '{!s}".format(\'test1\', \'test2\')\n' - ' "repr() shows quotes: \'test1\'; str() doesn\'t: test2"\n' - '\n' - 'Aligning the text and specifying a width:\n' - '\n' - " >>> '{:<30}'.format('left aligned')\n" - " 'left aligned '\n" - " >>> '{:>30}'.format('right aligned')\n" - " ' right aligned'\n" - " >>> '{:^30}'.format('centered')\n" - " ' centered '\n" - " >>> '{:*^30}'.format('centered') # use '*' as a fill " - 'char\n' - " '***********centered***********'\n" - '\n' - 'Replacing "%+f", "%-f", and "% f" and specifying a sign:\n' - '\n' - " >>> '{:+f}; {:+f}'.format(3.14, -3.14) # show it " - 'always\n' - " '+3.140000; -3.140000'\n" - " >>> '{: f}; {: f}'.format(3.14, -3.14) # show a space " - 'for positive numbers\n' - " ' 3.140000; -3.140000'\n" - " >>> '{:-f}; {:-f}'.format(3.14, -3.14) # show only the " - "minus -- same as '{:f}; {:f}'\n" - " '3.140000; -3.140000'\n" - '\n' - 'Replacing "%x" and "%o" and converting the value to ' - 'different bases:\n' - '\n' - ' >>> # format also supports binary numbers\n' - ' >>> "int: {0:d}; hex: {0:x}; oct: {0:o}; bin: ' - '{0:b}".format(42)\n' - " 'int: 42; hex: 2a; oct: 52; bin: 101010'\n" - ' >>> # with 0x, 0o, or 0b as prefix:\n' - ' >>> "int: {0:d}; hex: {0:#x}; oct: {0:#o}; bin: ' - '{0:#b}".format(42)\n' - " 'int: 42; hex: 0x2a; oct: 0o52; bin: 0b101010'\n" - '\n' - 'Using the comma as a thousands separator:\n' - '\n' - " >>> '{:,}'.format(1234567890)\n" - " '1,234,567,890'\n" - '\n' - 'Expressing a percentage:\n' - '\n' - ' >>> points = 19\n' - ' >>> total = 22\n' - " >>> 'Correct answers: {:.2%}'.format(points/total)\n" - " 'Correct answers: 86.36%'\n" - '\n' - 'Using type-specific formatting:\n' - '\n' - ' >>> import datetime\n' - ' >>> d = datetime.datetime(2010, 7, 4, 12, 15, 58)\n' - " >>> '{:%Y-%m-%d %H:%M:%S}'.format(d)\n" - " '2010-07-04 12:15:58'\n" - '\n' - 'Nesting arguments and more complex examples:\n' - '\n' - " >>> for align, text in zip('<^>', ['left', 'center', " - "'right']):\n" - " ... '{0:{fill}{align}16}'.format(text, fill=align, " - 'align=align)\n' - ' ...\n' - " 'left<<<<<<<<<<<<'\n" - " '^^^^^center^^^^^'\n" - " '>>>>>>>>>>>right'\n" - ' >>>\n' - ' >>> octets = [192, 168, 0, 1]\n' - " >>> '{:02X}{:02X}{:02X}{:02X}'.format(*octets)\n" - " 'C0A80001'\n" - ' >>> int(_, 16)\n' - ' 3232235521\n' - ' >>>\n' - ' >>> width = 5\n' - ' >>> for num in range(5,12): \n' - " ... for base in 'dXob':\n" - " ... print('{0:{width}{base}}'.format(num, " - "base=base, width=width), end=' ')\n" - ' ... print()\n' - ' ...\n' - ' 5 5 5 101\n' - ' 6 6 6 110\n' - ' 7 7 7 111\n' - ' 8 8 10 1000\n' - ' 9 9 11 1001\n' - ' 10 A 12 1010\n' - ' 11 B 13 1011\n', - 'function': 'Function definitions\n' - '********************\n' - '\n' - 'A function definition defines a user-defined function object ' - '(see\n' - 'section The standard type hierarchy):\n' - '\n' - ' funcdef ::= [decorators] "def" funcname "(" ' - '[parameter_list] ")"\n' - ' ["->" expression] ":" suite\n' - ' decorators ::= decorator+\n' - ' decorator ::= "@" assignment_expression ' - 'NEWLINE\n' - ' parameter_list ::= defparameter ("," ' - 'defparameter)* "," "/" ["," [parameter_list_no_posonly]]\n' - ' | parameter_list_no_posonly\n' - ' parameter_list_no_posonly ::= defparameter ("," ' - 'defparameter)* ["," [parameter_list_starargs]]\n' - ' | parameter_list_starargs\n' - ' parameter_list_starargs ::= "*" [parameter] ("," ' - 'defparameter)* ["," ["**" parameter [","]]]\n' - ' | "**" parameter [","]\n' - ' parameter ::= identifier [":" expression]\n' - ' defparameter ::= parameter ["=" expression]\n' - ' funcname ::= identifier\n' - '\n' - 'A function definition is an executable statement. Its execution ' - 'binds\n' - 'the function name in the current local namespace to a function ' - 'object\n' - '(a wrapper around the executable code for the function). This\n' - 'function object contains a reference to the current global ' - 'namespace\n' - 'as the global namespace to be used when the function is called.\n' - '\n' - 'The function definition does not execute the function body; this ' - 'gets\n' - 'executed only when the function is called. [4]\n' - '\n' - 'A function definition may be wrapped by one or more *decorator*\n' - 'expressions. Decorator expressions are evaluated when the ' - 'function is\n' - 'defined, in the scope that contains the function definition. ' - 'The\n' - 'result must be a callable, which is invoked with the function ' - 'object\n' - 'as the only argument. The returned value is bound to the ' - 'function name\n' - 'instead of the function object. Multiple decorators are applied ' - 'in\n' - 'nested fashion. For example, the following code\n' - '\n' - ' @f1(arg)\n' - ' @f2\n' - ' def func(): pass\n' - '\n' - 'is roughly equivalent to\n' - '\n' - ' def func(): pass\n' - ' func = f1(arg)(f2(func))\n' - '\n' - 'except that the original function is not temporarily bound to ' - 'the name\n' - '"func".\n' - '\n' - 'Changed in version 3.9: Functions may be decorated with any ' - 'valid\n' - '"assignment_expression". Previously, the grammar was much more\n' - 'restrictive; see **PEP 614** for details.\n' - '\n' - 'When one or more *parameters* have the form *parameter* "="\n' - '*expression*, the function is said to have “default parameter ' - 'values.”\n' - 'For a parameter with a default value, the corresponding ' - '*argument* may\n' - 'be omitted from a call, in which case the parameter’s default ' - 'value is\n' - 'substituted. If a parameter has a default value, all following\n' - 'parameters up until the “"*"” must also have a default value — ' - 'this is\n' - 'a syntactic restriction that is not expressed by the grammar.\n' - '\n' - '**Default parameter values are evaluated from left to right when ' - 'the\n' - 'function definition is executed.** This means that the ' - 'expression is\n' - 'evaluated once, when the function is defined, and that the same ' - '“pre-\n' - 'computed” value is used for each call. This is especially ' - 'important\n' - 'to understand when a default parameter value is a mutable ' - 'object, such\n' - 'as a list or a dictionary: if the function modifies the object ' - '(e.g.\n' - 'by appending an item to a list), the default parameter value is ' - 'in\n' - 'effect modified. This is generally not what was intended. A ' - 'way\n' - 'around this is to use "None" as the default, and explicitly test ' - 'for\n' - 'it in the body of the function, e.g.:\n' - '\n' - ' def whats_on_the_telly(penguin=None):\n' - ' if penguin is None:\n' - ' penguin = []\n' - ' penguin.append("property of the zoo")\n' - ' return penguin\n' - '\n' - 'Function call semantics are described in more detail in section ' - 'Calls.\n' - 'A function call always assigns values to all parameters ' - 'mentioned in\n' - 'the parameter list, either from positional arguments, from ' - 'keyword\n' - 'arguments, or from default values. If the form “"*identifier"” ' - 'is\n' - 'present, it is initialized to a tuple receiving any excess ' - 'positional\n' - 'parameters, defaulting to the empty tuple. If the form\n' - '“"**identifier"” is present, it is initialized to a new ordered\n' - 'mapping receiving any excess keyword arguments, defaulting to a ' - 'new\n' - 'empty mapping of the same type. Parameters after “"*"” or\n' - '“"*identifier"” are keyword-only parameters and may only be ' - 'passed by\n' - 'keyword arguments. Parameters before “"/"” are positional-only\n' - 'parameters and may only be passed by positional arguments.\n' - '\n' - 'Changed in version 3.8: The "/" function parameter syntax may be ' - 'used\n' - 'to indicate positional-only parameters. See **PEP 570** for ' - 'details.\n' - '\n' - 'Parameters may have an *annotation* of the form “": ' - 'expression"”\n' - 'following the parameter name. Any parameter may have an ' - 'annotation,\n' - 'even those of the form "*identifier" or "**identifier". ' - 'Functions may\n' - 'have “return” annotation of the form “"-> expression"” after ' - 'the\n' - 'parameter list. These annotations can be any valid Python ' - 'expression.\n' - 'The presence of annotations does not change the semantics of a\n' - 'function. The annotation values are available as values of a\n' - 'dictionary keyed by the parameters’ names in the ' - '"__annotations__"\n' - 'attribute of the function object. If the "annotations" import ' - 'from\n' - '"__future__" is used, annotations are preserved as strings at ' - 'runtime\n' - 'which enables postponed evaluation. Otherwise, they are ' - 'evaluated\n' - 'when the function definition is executed. In this case ' - 'annotations\n' - 'may be evaluated in a different order than they appear in the ' - 'source\n' - 'code.\n' - '\n' - 'It is also possible to create anonymous functions (functions not ' - 'bound\n' - 'to a name), for immediate use in expressions. This uses lambda\n' - 'expressions, described in section Lambdas. Note that the ' - 'lambda\n' - 'expression is merely a shorthand for a simplified function ' - 'definition;\n' - 'a function defined in a “"def"” statement can be passed around ' - 'or\n' - 'assigned to another name just like a function defined by a ' - 'lambda\n' - 'expression. The “"def"” form is actually more powerful since ' - 'it\n' - 'allows the execution of multiple statements and annotations.\n' - '\n' - '**Programmer’s note:** Functions are first-class objects. A ' - '“"def"”\n' - 'statement executed inside a function definition defines a local\n' - 'function that can be returned or passed around. Free variables ' - 'used\n' - 'in the nested function can access the local variables of the ' - 'function\n' - 'containing the def. See section Naming and binding for ' - 'details.\n' - '\n' - 'See also:\n' - '\n' - ' **PEP 3107** - Function Annotations\n' - ' The original specification for function annotations.\n' - '\n' - ' **PEP 484** - Type Hints\n' - ' Definition of a standard meaning for annotations: type ' - 'hints.\n' - '\n' - ' **PEP 526** - Syntax for Variable Annotations\n' - ' Ability to type hint variable declarations, including ' - 'class\n' - ' variables and instance variables\n' - '\n' - ' **PEP 563** - Postponed Evaluation of Annotations\n' - ' Support for forward references within annotations by ' - 'preserving\n' - ' annotations in a string form at runtime instead of eager\n' - ' evaluation.\n', - 'global': 'The "global" statement\n' - '**********************\n' - '\n' - ' global_stmt ::= "global" identifier ("," identifier)*\n' - '\n' - 'The "global" statement is a declaration which holds for the ' - 'entire\n' - 'current code block. It means that the listed identifiers are to ' - 'be\n' - 'interpreted as globals. It would be impossible to assign to a ' - 'global\n' - 'variable without "global", although free variables may refer to\n' - 'globals without being declared global.\n' - '\n' - 'Names listed in a "global" statement must not be used in the same ' - 'code\n' - 'block textually preceding that "global" statement.\n' - '\n' - 'Names listed in a "global" statement must not be defined as ' - 'formal\n' - 'parameters, or as targets in "with" statements or "except" ' - 'clauses, or\n' - 'in a "for" target list, "class" definition, function definition,\n' - '"import" statement, or variable annotation.\n' - '\n' - '**CPython implementation detail:** The current implementation does ' - 'not\n' - 'enforce some of these restrictions, but programs should not abuse ' - 'this\n' - 'freedom, as future implementations may enforce them or silently ' - 'change\n' - 'the meaning of the program.\n' - '\n' - '**Programmer’s note:** "global" is a directive to the parser. It\n' - 'applies only to code parsed at the same time as the "global"\n' - 'statement. In particular, a "global" statement contained in a ' - 'string\n' - 'or code object supplied to the built-in "exec()" function does ' - 'not\n' - 'affect the code block *containing* the function call, and code\n' - 'contained in such a string is unaffected by "global" statements in ' - 'the\n' - 'code containing the function call. The same applies to the ' - '"eval()"\n' - 'and "compile()" functions.\n', - 'id-classes': 'Reserved classes of identifiers\n' - '*******************************\n' - '\n' - 'Certain classes of identifiers (besides keywords) have ' - 'special\n' - 'meanings. These classes are identified by the patterns of ' - 'leading and\n' - 'trailing underscore characters:\n' - '\n' - '"_*"\n' - ' Not imported by "from module import *".\n' - '\n' - '"_"\n' - ' In a "case" pattern within a "match" statement, "_" is a ' - 'soft\n' - ' keyword that denotes a wildcard.\n' - '\n' - ' Separately, the interactive interpreter makes the result of ' - 'the\n' - ' last evaluation available in the variable "_". (It is ' - 'stored in the\n' - ' "builtins" module, alongside built-in functions like ' - '"print".)\n' - '\n' - ' Elsewhere, "_" is a regular identifier. It is often used to ' - 'name\n' - ' “special” items, but it is not special to Python itself.\n' - '\n' - ' Note:\n' - '\n' - ' The name "_" is often used in conjunction with\n' - ' internationalization; refer to the documentation for the\n' - ' "gettext" module for more information on this ' - 'convention.It is\n' - ' also commonly used for unused variables.\n' - '\n' - '"__*__"\n' - ' System-defined names, informally known as “dunder” names. ' - 'These\n' - ' names are defined by the interpreter and its ' - 'implementation\n' - ' (including the standard library). Current system names are\n' - ' discussed in the Special method names section and ' - 'elsewhere. More\n' - ' will likely be defined in future versions of Python. *Any* ' - 'use of\n' - ' "__*__" names, in any context, that does not follow ' - 'explicitly\n' - ' documented use, is subject to breakage without warning.\n' - '\n' - '"__*"\n' - ' Class-private names. Names in this category, when used ' - 'within the\n' - ' context of a class definition, are re-written to use a ' - 'mangled form\n' - ' to help avoid name clashes between “private” attributes of ' - 'base and\n' - ' derived classes. See section Identifiers (Names).\n', - 'identifiers': 'Identifiers and keywords\n' - '************************\n' - '\n' - 'Identifiers (also referred to as *names*) are described by ' - 'the\n' - 'following lexical definitions.\n' - '\n' - 'The syntax of identifiers in Python is based on the Unicode ' - 'standard\n' - 'annex UAX-31, with elaboration and changes as defined below; ' - 'see also\n' - '**PEP 3131** for further details.\n' - '\n' - 'Within the ASCII range (U+0001..U+007F), the valid characters ' - 'for\n' - 'identifiers are the same as in Python 2.x: the uppercase and ' - 'lowercase\n' - 'letters "A" through "Z", the underscore "_" and, except for ' - 'the first\n' - 'character, the digits "0" through "9".\n' - '\n' - 'Python 3.0 introduces additional characters from outside the ' - 'ASCII\n' - 'range (see **PEP 3131**). For these characters, the ' - 'classification\n' - 'uses the version of the Unicode Character Database as ' - 'included in the\n' - '"unicodedata" module.\n' - '\n' - 'Identifiers are unlimited in length. Case is significant.\n' - '\n' - ' identifier ::= xid_start xid_continue*\n' - ' id_start ::= <all characters in general categories Lu, ' - 'Ll, Lt, Lm, Lo, Nl, the underscore, and characters with the ' - 'Other_ID_Start property>\n' - ' id_continue ::= <all characters in id_start, plus ' - 'characters in the categories Mn, Mc, Nd, Pc and others with ' - 'the Other_ID_Continue property>\n' - ' xid_start ::= <all characters in id_start whose NFKC ' - 'normalization is in "id_start xid_continue*">\n' - ' xid_continue ::= <all characters in id_continue whose NFKC ' - 'normalization is in "id_continue*">\n' - '\n' - 'The Unicode category codes mentioned above stand for:\n' - '\n' - '* *Lu* - uppercase letters\n' - '\n' - '* *Ll* - lowercase letters\n' - '\n' - '* *Lt* - titlecase letters\n' - '\n' - '* *Lm* - modifier letters\n' - '\n' - '* *Lo* - other letters\n' - '\n' - '* *Nl* - letter numbers\n' - '\n' - '* *Mn* - nonspacing marks\n' - '\n' - '* *Mc* - spacing combining marks\n' - '\n' - '* *Nd* - decimal numbers\n' - '\n' - '* *Pc* - connector punctuations\n' - '\n' - '* *Other_ID_Start* - explicit list of characters in ' - 'PropList.txt to\n' - ' support backwards compatibility\n' - '\n' - '* *Other_ID_Continue* - likewise\n' - '\n' - 'All identifiers are converted into the normal form NFKC while ' - 'parsing;\n' - 'comparison of identifiers is based on NFKC.\n' - '\n' - 'A non-normative HTML file listing all valid identifier ' - 'characters for\n' - 'Unicode 4.1 can be found at\n' - 'https://www.unicode.org/Public/13.0.0/ucd/DerivedCoreProperties.txt\n' - '\n' - '\n' - 'Keywords\n' - '========\n' - '\n' - 'The following identifiers are used as reserved words, or ' - '*keywords* of\n' - 'the language, and cannot be used as ordinary identifiers. ' - 'They must\n' - 'be spelled exactly as written here:\n' - '\n' - ' False await else import pass\n' - ' None break except in raise\n' - ' True class finally is return\n' - ' and continue for lambda try\n' - ' as def from nonlocal while\n' - ' assert del global not with\n' - ' async elif if or yield\n' - '\n' - '\n' - 'Soft Keywords\n' - '=============\n' - '\n' - 'New in version 3.10.\n' - '\n' - 'Some identifiers are only reserved under specific contexts. ' - 'These are\n' - 'known as *soft keywords*. The identifiers "match", "case" ' - 'and "_" can\n' - 'syntactically act as keywords in contexts related to the ' - 'pattern\n' - 'matching statement, but this distinction is done at the ' - 'parser level,\n' - 'not when tokenizing.\n' - '\n' - 'As soft keywords, their use with pattern matching is possible ' - 'while\n' - 'still preserving compatibility with existing code that uses ' - '"match",\n' - '"case" and "_" as identifier names.\n' - '\n' - '\n' - 'Reserved classes of identifiers\n' - '===============================\n' - '\n' - 'Certain classes of identifiers (besides keywords) have ' - 'special\n' - 'meanings. These classes are identified by the patterns of ' - 'leading and\n' - 'trailing underscore characters:\n' - '\n' - '"_*"\n' - ' Not imported by "from module import *".\n' - '\n' - '"_"\n' - ' In a "case" pattern within a "match" statement, "_" is a ' - 'soft\n' - ' keyword that denotes a wildcard.\n' - '\n' - ' Separately, the interactive interpreter makes the result ' - 'of the\n' - ' last evaluation available in the variable "_". (It is ' - 'stored in the\n' - ' "builtins" module, alongside built-in functions like ' - '"print".)\n' - '\n' - ' Elsewhere, "_" is a regular identifier. It is often used ' - 'to name\n' - ' “special” items, but it is not special to Python itself.\n' - '\n' - ' Note:\n' - '\n' - ' The name "_" is often used in conjunction with\n' - ' internationalization; refer to the documentation for ' - 'the\n' - ' "gettext" module for more information on this ' - 'convention.It is\n' - ' also commonly used for unused variables.\n' - '\n' - '"__*__"\n' - ' System-defined names, informally known as “dunder” names. ' - 'These\n' - ' names are defined by the interpreter and its ' - 'implementation\n' - ' (including the standard library). Current system names ' - 'are\n' - ' discussed in the Special method names section and ' - 'elsewhere. More\n' - ' will likely be defined in future versions of Python. ' - '*Any* use of\n' - ' "__*__" names, in any context, that does not follow ' - 'explicitly\n' - ' documented use, is subject to breakage without warning.\n' - '\n' - '"__*"\n' - ' Class-private names. Names in this category, when used ' - 'within the\n' - ' context of a class definition, are re-written to use a ' - 'mangled form\n' - ' to help avoid name clashes between “private” attributes of ' - 'base and\n' - ' derived classes. See section Identifiers (Names).\n', - 'if': 'The "if" statement\n' - '******************\n' - '\n' - 'The "if" statement is used for conditional execution:\n' - '\n' - ' if_stmt ::= "if" assignment_expression ":" suite\n' - ' ("elif" assignment_expression ":" suite)*\n' - ' ["else" ":" suite]\n' - '\n' - 'It selects exactly one of the suites by evaluating the expressions ' - 'one\n' - 'by one until one is found to be true (see section Boolean operations\n' - 'for the definition of true and false); then that suite is executed\n' - '(and no other part of the "if" statement is executed or evaluated).\n' - 'If all expressions are false, the suite of the "else" clause, if\n' - 'present, is executed.\n', - 'imaginary': 'Imaginary literals\n' - '******************\n' - '\n' - 'Imaginary literals are described by the following lexical ' - 'definitions:\n' - '\n' - ' imagnumber ::= (floatnumber | digitpart) ("j" | "J")\n' - '\n' - 'An imaginary literal yields a complex number with a real part ' - 'of 0.0.\n' - 'Complex numbers are represented as a pair of floating point ' - 'numbers\n' - 'and have the same restrictions on their range. To create a ' - 'complex\n' - 'number with a nonzero real part, add a floating point number to ' - 'it,\n' - 'e.g., "(3+4j)". Some examples of imaginary literals:\n' - '\n' - ' 3.14j 10.j 10j .001j 1e100j 3.14e-10j ' - '3.14_15_93j\n', - 'import': 'The "import" statement\n' - '**********************\n' - '\n' - ' import_stmt ::= "import" module ["as" identifier] ("," ' - 'module ["as" identifier])*\n' - ' | "from" relative_module "import" identifier ' - '["as" identifier]\n' - ' ("," identifier ["as" identifier])*\n' - ' | "from" relative_module "import" "(" ' - 'identifier ["as" identifier]\n' - ' ("," identifier ["as" identifier])* [","] ")"\n' - ' | "from" relative_module "import" "*"\n' - ' module ::= (identifier ".")* identifier\n' - ' relative_module ::= "."* module | "."+\n' - '\n' - 'The basic import statement (no "from" clause) is executed in two\n' - 'steps:\n' - '\n' - '1. find a module, loading and initializing it if necessary\n' - '\n' - '2. define a name or names in the local namespace for the scope ' - 'where\n' - ' the "import" statement occurs.\n' - '\n' - 'When the statement contains multiple clauses (separated by commas) ' - 'the\n' - 'two steps are carried out separately for each clause, just as ' - 'though\n' - 'the clauses had been separated out into individual import ' - 'statements.\n' - '\n' - 'The details of the first step, finding and loading modules are\n' - 'described in greater detail in the section on the import system, ' - 'which\n' - 'also describes the various types of packages and modules that can ' - 'be\n' - 'imported, as well as all the hooks that can be used to customize ' - 'the\n' - 'import system. Note that failures in this step may indicate ' - 'either\n' - 'that the module could not be located, *or* that an error occurred\n' - 'while initializing the module, which includes execution of the\n' - 'module’s code.\n' - '\n' - 'If the requested module is retrieved successfully, it will be ' - 'made\n' - 'available in the local namespace in one of three ways:\n' - '\n' - '* If the module name is followed by "as", then the name following ' - '"as"\n' - ' is bound directly to the imported module.\n' - '\n' - '* If no other name is specified, and the module being imported is ' - 'a\n' - ' top level module, the module’s name is bound in the local ' - 'namespace\n' - ' as a reference to the imported module\n' - '\n' - '* If the module being imported is *not* a top level module, then ' - 'the\n' - ' name of the top level package that contains the module is bound ' - 'in\n' - ' the local namespace as a reference to the top level package. ' - 'The\n' - ' imported module must be accessed using its full qualified name\n' - ' rather than directly\n' - '\n' - 'The "from" form uses a slightly more complex process:\n' - '\n' - '1. find the module specified in the "from" clause, loading and\n' - ' initializing it if necessary;\n' - '\n' - '2. for each of the identifiers specified in the "import" clauses:\n' - '\n' - ' 1. check if the imported module has an attribute by that name\n' - '\n' - ' 2. if not, attempt to import a submodule with that name and ' - 'then\n' - ' check the imported module again for that attribute\n' - '\n' - ' 3. if the attribute is not found, "ImportError" is raised.\n' - '\n' - ' 4. otherwise, a reference to that value is stored in the local\n' - ' namespace, using the name in the "as" clause if it is ' - 'present,\n' - ' otherwise using the attribute name\n' - '\n' - 'Examples:\n' - '\n' - ' import foo # foo imported and bound locally\n' - ' import foo.bar.baz # foo, foo.bar, and foo.bar.baz ' - 'imported, foo bound locally\n' - ' import foo.bar.baz as fbb # foo, foo.bar, and foo.bar.baz ' - 'imported, foo.bar.baz bound as fbb\n' - ' from foo.bar import baz # foo, foo.bar, and foo.bar.baz ' - 'imported, foo.bar.baz bound as baz\n' - ' from foo import attr # foo imported and foo.attr bound as ' - 'attr\n' - '\n' - 'If the list of identifiers is replaced by a star ("\'*\'"), all ' - 'public\n' - 'names defined in the module are bound in the local namespace for ' - 'the\n' - 'scope where the "import" statement occurs.\n' - '\n' - 'The *public names* defined by a module are determined by checking ' - 'the\n' - 'module’s namespace for a variable named "__all__"; if defined, it ' - 'must\n' - 'be a sequence of strings which are names defined or imported by ' - 'that\n' - 'module. The names given in "__all__" are all considered public ' - 'and\n' - 'are required to exist. If "__all__" is not defined, the set of ' - 'public\n' - 'names includes all names found in the module’s namespace which do ' - 'not\n' - 'begin with an underscore character ("\'_\'"). "__all__" should ' - 'contain\n' - 'the entire public API. It is intended to avoid accidentally ' - 'exporting\n' - 'items that are not part of the API (such as library modules which ' - 'were\n' - 'imported and used within the module).\n' - '\n' - 'The wild card form of import — "from module import *" — is only\n' - 'allowed at the module level. Attempting to use it in class or\n' - 'function definitions will raise a "SyntaxError".\n' - '\n' - 'When specifying what module to import you do not have to specify ' - 'the\n' - 'absolute name of the module. When a module or package is ' - 'contained\n' - 'within another package it is possible to make a relative import ' - 'within\n' - 'the same top package without having to mention the package name. ' - 'By\n' - 'using leading dots in the specified module or package after "from" ' - 'you\n' - 'can specify how high to traverse up the current package hierarchy\n' - 'without specifying exact names. One leading dot means the current\n' - 'package where the module making the import exists. Two dots means ' - 'up\n' - 'one package level. Three dots is up two levels, etc. So if you ' - 'execute\n' - '"from . import mod" from a module in the "pkg" package then you ' - 'will\n' - 'end up importing "pkg.mod". If you execute "from ..subpkg2 import ' - 'mod"\n' - 'from within "pkg.subpkg1" you will import "pkg.subpkg2.mod". The\n' - 'specification for relative imports is contained in the Package\n' - 'Relative Imports section.\n' - '\n' - '"importlib.import_module()" is provided to support applications ' - 'that\n' - 'determine dynamically the modules to be loaded.\n' - '\n' - 'Raises an auditing event "import" with arguments "module", ' - '"filename",\n' - '"sys.path", "sys.meta_path", "sys.path_hooks".\n' - '\n' - '\n' - 'Future statements\n' - '=================\n' - '\n' - 'A *future statement* is a directive to the compiler that a ' - 'particular\n' - 'module should be compiled using syntax or semantics that will be\n' - 'available in a specified future release of Python where the ' - 'feature\n' - 'becomes standard.\n' - '\n' - 'The future statement is intended to ease migration to future ' - 'versions\n' - 'of Python that introduce incompatible changes to the language. ' - 'It\n' - 'allows use of the new features on a per-module basis before the\n' - 'release in which the feature becomes standard.\n' - '\n' - ' future_stmt ::= "from" "__future__" "import" feature ["as" ' - 'identifier]\n' - ' ("," feature ["as" identifier])*\n' - ' | "from" "__future__" "import" "(" feature ' - '["as" identifier]\n' - ' ("," feature ["as" identifier])* [","] ")"\n' - ' feature ::= identifier\n' - '\n' - 'A future statement must appear near the top of the module. The ' - 'only\n' - 'lines that can appear before a future statement are:\n' - '\n' - '* the module docstring (if any),\n' - '\n' - '* comments,\n' - '\n' - '* blank lines, and\n' - '\n' - '* other future statements.\n' - '\n' - 'The only feature that requires using the future statement is\n' - '"annotations" (see **PEP 563**).\n' - '\n' - 'All historical features enabled by the future statement are still\n' - 'recognized by Python 3. The list includes "absolute_import",\n' - '"division", "generators", "generator_stop", "unicode_literals",\n' - '"print_function", "nested_scopes" and "with_statement". They are ' - 'all\n' - 'redundant because they are always enabled, and only kept for ' - 'backwards\n' - 'compatibility.\n' - '\n' - 'A future statement is recognized and treated specially at compile\n' - 'time: Changes to the semantics of core constructs are often\n' - 'implemented by generating different code. It may even be the ' - 'case\n' - 'that a new feature introduces new incompatible syntax (such as a ' - 'new\n' - 'reserved word), in which case the compiler may need to parse the\n' - 'module differently. Such decisions cannot be pushed off until\n' - 'runtime.\n' - '\n' - 'For any given release, the compiler knows which feature names ' - 'have\n' - 'been defined, and raises a compile-time error if a future ' - 'statement\n' - 'contains a feature not known to it.\n' - '\n' - 'The direct runtime semantics are the same as for any import ' - 'statement:\n' - 'there is a standard module "__future__", described later, and it ' - 'will\n' - 'be imported in the usual way at the time the future statement is\n' - 'executed.\n' - '\n' - 'The interesting runtime semantics depend on the specific feature\n' - 'enabled by the future statement.\n' - '\n' - 'Note that there is nothing special about the statement:\n' - '\n' - ' import __future__ [as name]\n' - '\n' - 'That is not a future statement; it’s an ordinary import statement ' - 'with\n' - 'no special semantics or syntax restrictions.\n' - '\n' - 'Code compiled by calls to the built-in functions "exec()" and\n' - '"compile()" that occur in a module "M" containing a future ' - 'statement\n' - 'will, by default, use the new syntax or semantics associated with ' - 'the\n' - 'future statement. This can be controlled by optional arguments ' - 'to\n' - '"compile()" — see the documentation of that function for details.\n' - '\n' - 'A future statement typed at an interactive interpreter prompt ' - 'will\n' - 'take effect for the rest of the interpreter session. If an\n' - 'interpreter is started with the "-i" option, is passed a script ' - 'name\n' - 'to execute, and the script includes a future statement, it will be ' - 'in\n' - 'effect in the interactive session started after the script is\n' - 'executed.\n' - '\n' - 'See also:\n' - '\n' - ' **PEP 236** - Back to the __future__\n' - ' The original proposal for the __future__ mechanism.\n', - 'in': 'Membership test operations\n' - '**************************\n' - '\n' - 'The operators "in" and "not in" test for membership. "x in s"\n' - 'evaluates to "True" if *x* is a member of *s*, and "False" otherwise.\n' - '"x not in s" returns the negation of "x in s". All built-in ' - 'sequences\n' - 'and set types support this as well as dictionary, for which "in" ' - 'tests\n' - 'whether the dictionary has a given key. For container types such as\n' - 'list, tuple, set, frozenset, dict, or collections.deque, the\n' - 'expression "x in y" is equivalent to "any(x is e or x == e for e in\n' - 'y)".\n' - '\n' - 'For the string and bytes types, "x in y" is "True" if and only if *x*\n' - 'is a substring of *y*. An equivalent test is "y.find(x) != -1".\n' - 'Empty strings are always considered to be a substring of any other\n' - 'string, so """ in "abc"" will return "True".\n' - '\n' - 'For user-defined classes which define the "__contains__()" method, "x\n' - 'in y" returns "True" if "y.__contains__(x)" returns a true value, and\n' - '"False" otherwise.\n' - '\n' - 'For user-defined classes which do not define "__contains__()" but do\n' - 'define "__iter__()", "x in y" is "True" if some value "z", for which\n' - 'the expression "x is z or x == z" is true, is produced while ' - 'iterating\n' - 'over "y". If an exception is raised during the iteration, it is as if\n' - '"in" raised that exception.\n' - '\n' - 'Lastly, the old-style iteration protocol is tried: if a class defines\n' - '"__getitem__()", "x in y" is "True" if and only if there is a non-\n' - 'negative integer index *i* such that "x is y[i] or x == y[i]", and no\n' - 'lower integer index raises the "IndexError" exception. (If any other\n' - 'exception is raised, it is as if "in" raised that exception).\n' - '\n' - 'The operator "not in" is defined to have the inverse truth value of\n' - '"in".\n', - 'integers': 'Integer literals\n' - '****************\n' - '\n' - 'Integer literals are described by the following lexical ' - 'definitions:\n' - '\n' - ' integer ::= decinteger | bininteger | octinteger | ' - 'hexinteger\n' - ' decinteger ::= nonzerodigit (["_"] digit)* | "0"+ (["_"] ' - '"0")*\n' - ' bininteger ::= "0" ("b" | "B") (["_"] bindigit)+\n' - ' octinteger ::= "0" ("o" | "O") (["_"] octdigit)+\n' - ' hexinteger ::= "0" ("x" | "X") (["_"] hexdigit)+\n' - ' nonzerodigit ::= "1"..."9"\n' - ' digit ::= "0"..."9"\n' - ' bindigit ::= "0" | "1"\n' - ' octdigit ::= "0"..."7"\n' - ' hexdigit ::= digit | "a"..."f" | "A"..."F"\n' - '\n' - 'There is no limit for the length of integer literals apart from ' - 'what\n' - 'can be stored in available memory.\n' - '\n' - 'Underscores are ignored for determining the numeric value of ' - 'the\n' - 'literal. They can be used to group digits for enhanced ' - 'readability.\n' - 'One underscore can occur between digits, and after base ' - 'specifiers\n' - 'like "0x".\n' - '\n' - 'Note that leading zeros in a non-zero decimal number are not ' - 'allowed.\n' - 'This is for disambiguation with C-style octal literals, which ' - 'Python\n' - 'used before version 3.0.\n' - '\n' - 'Some examples of integer literals:\n' - '\n' - ' 7 2147483647 0o177 0b100110111\n' - ' 3 79228162514264337593543950336 0o377 0xdeadbeef\n' - ' 100_000_000_000 0b_1110_0101\n' - '\n' - 'Changed in version 3.6: Underscores are now allowed for ' - 'grouping\n' - 'purposes in literals.\n', - 'lambda': 'Lambdas\n' - '*******\n' - '\n' - ' lambda_expr ::= "lambda" [parameter_list] ":" expression\n' - '\n' - 'Lambda expressions (sometimes called lambda forms) are used to ' - 'create\n' - 'anonymous functions. The expression "lambda parameters: ' - 'expression"\n' - 'yields a function object. The unnamed object behaves like a ' - 'function\n' - 'object defined with:\n' - '\n' - ' def <lambda>(parameters):\n' - ' return expression\n' - '\n' - 'See section Function definitions for the syntax of parameter ' - 'lists.\n' - 'Note that functions created with lambda expressions cannot ' - 'contain\n' - 'statements or annotations.\n', - 'lists': 'List displays\n' - '*************\n' - '\n' - 'A list display is a possibly empty series of expressions enclosed ' - 'in\n' - 'square brackets:\n' - '\n' - ' list_display ::= "[" [starred_list | comprehension] "]"\n' - '\n' - 'A list display yields a new list object, the contents being ' - 'specified\n' - 'by either a list of expressions or a comprehension. When a comma-\n' - 'separated list of expressions is supplied, its elements are ' - 'evaluated\n' - 'from left to right and placed into the list object in that order.\n' - 'When a comprehension is supplied, the list is constructed from the\n' - 'elements resulting from the comprehension.\n', - 'naming': 'Naming and binding\n' - '******************\n' - '\n' - '\n' - 'Binding of names\n' - '================\n' - '\n' - '*Names* refer to objects. Names are introduced by name binding\n' - 'operations.\n' - '\n' - 'The following constructs bind names:\n' - '\n' - '* formal parameters to functions,\n' - '\n' - '* class definitions,\n' - '\n' - '* function definitions,\n' - '\n' - '* assignment expressions,\n' - '\n' - '* targets that are identifiers if occurring in an assignment:\n' - '\n' - ' * "for" loop header,\n' - '\n' - ' * after "as" in a "with" statement, "except" clause or in the ' - 'as-\n' - ' pattern in structural pattern matching,\n' - '\n' - ' * in a capture pattern in structural pattern matching\n' - '\n' - '* "import" statements.\n' - '\n' - 'The "import" statement of the form "from ... import *" binds all ' - 'names\n' - 'defined in the imported module, except those beginning with an\n' - 'underscore. This form may only be used at the module level.\n' - '\n' - 'A target occurring in a "del" statement is also considered bound ' - 'for\n' - 'this purpose (though the actual semantics are to unbind the ' - 'name).\n' - '\n' - 'Each assignment or import statement occurs within a block defined ' - 'by a\n' - 'class or function definition or at the module level (the ' - 'top-level\n' - 'code block).\n' - '\n' - 'If a name is bound in a block, it is a local variable of that ' - 'block,\n' - 'unless declared as "nonlocal" or "global". If a name is bound at ' - 'the\n' - 'module level, it is a global variable. (The variables of the ' - 'module\n' - 'code block are local and global.) If a variable is used in a ' - 'code\n' - 'block but not defined there, it is a *free variable*.\n' - '\n' - 'Each occurrence of a name in the program text refers to the ' - '*binding*\n' - 'of that name established by the following name resolution rules.\n' - '\n' - '\n' - 'Resolution of names\n' - '===================\n' - '\n' - 'A *scope* defines the visibility of a name within a block. If a ' - 'local\n' - 'variable is defined in a block, its scope includes that block. If ' - 'the\n' - 'definition occurs in a function block, the scope extends to any ' - 'blocks\n' - 'contained within the defining one, unless a contained block ' - 'introduces\n' - 'a different binding for the name.\n' - '\n' - 'When a name is used in a code block, it is resolved using the ' - 'nearest\n' - 'enclosing scope. The set of all such scopes visible to a code ' - 'block\n' - 'is called the block’s *environment*.\n' - '\n' - 'When a name is not found at all, a "NameError" exception is ' - 'raised. If\n' - 'the current scope is a function scope, and the name refers to a ' - 'local\n' - 'variable that has not yet been bound to a value at the point where ' - 'the\n' - 'name is used, an "UnboundLocalError" exception is raised.\n' - '"UnboundLocalError" is a subclass of "NameError".\n' - '\n' - 'If a name binding operation occurs anywhere within a code block, ' - 'all\n' - 'uses of the name within the block are treated as references to ' - 'the\n' - 'current block. This can lead to errors when a name is used within ' - 'a\n' - 'block before it is bound. This rule is subtle. Python lacks\n' - 'declarations and allows name binding operations to occur anywhere\n' - 'within a code block. The local variables of a code block can be\n' - 'determined by scanning the entire text of the block for name ' - 'binding\n' - 'operations.\n' - '\n' - 'If the "global" statement occurs within a block, all uses of the ' - 'names\n' - 'specified in the statement refer to the bindings of those names in ' - 'the\n' - 'top-level namespace. Names are resolved in the top-level ' - 'namespace by\n' - 'searching the global namespace, i.e. the namespace of the module\n' - 'containing the code block, and the builtins namespace, the ' - 'namespace\n' - 'of the module "builtins". The global namespace is searched ' - 'first. If\n' - 'the names are not found there, the builtins namespace is ' - 'searched.\n' - 'The "global" statement must precede all uses of the listed names.\n' - '\n' - 'The "global" statement has the same scope as a name binding ' - 'operation\n' - 'in the same block. If the nearest enclosing scope for a free ' - 'variable\n' - 'contains a global statement, the free variable is treated as a ' - 'global.\n' - '\n' - 'The "nonlocal" statement causes corresponding names to refer to\n' - 'previously bound variables in the nearest enclosing function ' - 'scope.\n' - '"SyntaxError" is raised at compile time if the given name does ' - 'not\n' - 'exist in any enclosing function scope.\n' - '\n' - 'The namespace for a module is automatically created the first time ' - 'a\n' - 'module is imported. The main module for a script is always ' - 'called\n' - '"__main__".\n' - '\n' - 'Class definition blocks and arguments to "exec()" and "eval()" ' - 'are\n' - 'special in the context of name resolution. A class definition is ' - 'an\n' - 'executable statement that may use and define names. These ' - 'references\n' - 'follow the normal rules for name resolution with an exception ' - 'that\n' - 'unbound local variables are looked up in the global namespace. ' - 'The\n' - 'namespace of the class definition becomes the attribute dictionary ' - 'of\n' - 'the class. The scope of names defined in a class block is limited ' - 'to\n' - 'the class block; it does not extend to the code blocks of methods ' - '–\n' - 'this includes comprehensions and generator expressions since they ' - 'are\n' - 'implemented using a function scope. This means that the ' - 'following\n' - 'will fail:\n' - '\n' - ' class A:\n' - ' a = 42\n' - ' b = list(a + i for i in range(10))\n' - '\n' - '\n' - 'Builtins and restricted execution\n' - '=================================\n' - '\n' - '**CPython implementation detail:** Users should not touch\n' - '"__builtins__"; it is strictly an implementation detail. Users\n' - 'wanting to override values in the builtins namespace should ' - '"import"\n' - 'the "builtins" module and modify its attributes appropriately.\n' - '\n' - 'The builtins namespace associated with the execution of a code ' - 'block\n' - 'is actually found by looking up the name "__builtins__" in its ' - 'global\n' - 'namespace; this should be a dictionary or a module (in the latter ' - 'case\n' - 'the module’s dictionary is used). By default, when in the ' - '"__main__"\n' - 'module, "__builtins__" is the built-in module "builtins"; when in ' - 'any\n' - 'other module, "__builtins__" is an alias for the dictionary of ' - 'the\n' - '"builtins" module itself.\n' - '\n' - '\n' - 'Interaction with dynamic features\n' - '=================================\n' - '\n' - 'Name resolution of free variables occurs at runtime, not at ' - 'compile\n' - 'time. This means that the following code will print 42:\n' - '\n' - ' i = 10\n' - ' def f():\n' - ' print(i)\n' - ' i = 42\n' - ' f()\n' - '\n' - 'The "eval()" and "exec()" functions do not have access to the ' - 'full\n' - 'environment for resolving names. Names may be resolved in the ' - 'local\n' - 'and global namespaces of the caller. Free variables are not ' - 'resolved\n' - 'in the nearest enclosing namespace, but in the global namespace. ' - '[1]\n' - 'The "exec()" and "eval()" functions have optional arguments to\n' - 'override the global and local namespace. If only one namespace ' - 'is\n' - 'specified, it is used for both.\n', - 'nonlocal': 'The "nonlocal" statement\n' - '************************\n' - '\n' - ' nonlocal_stmt ::= "nonlocal" identifier ("," identifier)*\n' - '\n' - 'The "nonlocal" statement causes the listed identifiers to refer ' - 'to\n' - 'previously bound variables in the nearest enclosing scope ' - 'excluding\n' - 'globals. This is important because the default behavior for ' - 'binding is\n' - 'to search the local namespace first. The statement allows\n' - 'encapsulated code to rebind variables outside of the local ' - 'scope\n' - 'besides the global (module) scope.\n' - '\n' - 'Names listed in a "nonlocal" statement, unlike those listed in ' - 'a\n' - '"global" statement, must refer to pre-existing bindings in an\n' - 'enclosing scope (the scope in which a new binding should be ' - 'created\n' - 'cannot be determined unambiguously).\n' - '\n' - 'Names listed in a "nonlocal" statement must not collide with ' - 'pre-\n' - 'existing bindings in the local scope.\n' - '\n' - 'See also:\n' - '\n' - ' **PEP 3104** - Access to Names in Outer Scopes\n' - ' The specification for the "nonlocal" statement.\n', - 'numbers': 'Numeric literals\n' - '****************\n' - '\n' - 'There are three types of numeric literals: integers, floating ' - 'point\n' - 'numbers, and imaginary numbers. There are no complex literals\n' - '(complex numbers can be formed by adding a real number and an\n' - 'imaginary number).\n' - '\n' - 'Note that numeric literals do not include a sign; a phrase like ' - '"-1"\n' - 'is actually an expression composed of the unary operator ‘"-"’ ' - 'and the\n' - 'literal "1".\n', - 'numeric-types': 'Emulating numeric types\n' - '***********************\n' - '\n' - 'The following methods can be defined to emulate numeric ' - 'objects.\n' - 'Methods corresponding to operations that are not supported ' - 'by the\n' - 'particular kind of number implemented (e.g., bitwise ' - 'operations for\n' - 'non-integral numbers) should be left undefined.\n' - '\n' - 'object.__add__(self, other)\n' - 'object.__sub__(self, other)\n' - 'object.__mul__(self, other)\n' - 'object.__matmul__(self, other)\n' - 'object.__truediv__(self, other)\n' - 'object.__floordiv__(self, other)\n' - 'object.__mod__(self, other)\n' - 'object.__divmod__(self, other)\n' - 'object.__pow__(self, other[, modulo])\n' - 'object.__lshift__(self, other)\n' - 'object.__rshift__(self, other)\n' - 'object.__and__(self, other)\n' - 'object.__xor__(self, other)\n' - 'object.__or__(self, other)\n' - '\n' - ' These methods are called to implement the binary ' - 'arithmetic\n' - ' operations ("+", "-", "*", "@", "/", "//", "%", ' - '"divmod()",\n' - ' "pow()", "**", "<<", ">>", "&", "^", "|"). For ' - 'instance, to\n' - ' evaluate the expression "x + y", where *x* is an ' - 'instance of a\n' - ' class that has an "__add__()" method, "x.__add__(y)" is ' - 'called.\n' - ' The "__divmod__()" method should be the equivalent to ' - 'using\n' - ' "__floordiv__()" and "__mod__()"; it should not be ' - 'related to\n' - ' "__truediv__()". Note that "__pow__()" should be ' - 'defined to accept\n' - ' an optional third argument if the ternary version of the ' - 'built-in\n' - ' "pow()" function is to be supported.\n' - '\n' - ' If one of those methods does not support the operation ' - 'with the\n' - ' supplied arguments, it should return "NotImplemented".\n' - '\n' - 'object.__radd__(self, other)\n' - 'object.__rsub__(self, other)\n' - 'object.__rmul__(self, other)\n' - 'object.__rmatmul__(self, other)\n' - 'object.__rtruediv__(self, other)\n' - 'object.__rfloordiv__(self, other)\n' - 'object.__rmod__(self, other)\n' - 'object.__rdivmod__(self, other)\n' - 'object.__rpow__(self, other[, modulo])\n' - 'object.__rlshift__(self, other)\n' - 'object.__rrshift__(self, other)\n' - 'object.__rand__(self, other)\n' - 'object.__rxor__(self, other)\n' - 'object.__ror__(self, other)\n' - '\n' - ' These methods are called to implement the binary ' - 'arithmetic\n' - ' operations ("+", "-", "*", "@", "/", "//", "%", ' - '"divmod()",\n' - ' "pow()", "**", "<<", ">>", "&", "^", "|") with reflected ' - '(swapped)\n' - ' operands. These functions are only called if the left ' - 'operand does\n' - ' not support the corresponding operation [3] and the ' - 'operands are of\n' - ' different types. [4] For instance, to evaluate the ' - 'expression "x -\n' - ' y", where *y* is an instance of a class that has an ' - '"__rsub__()"\n' - ' method, "y.__rsub__(x)" is called if "x.__sub__(y)" ' - 'returns\n' - ' *NotImplemented*.\n' - '\n' - ' Note that ternary "pow()" will not try calling ' - '"__rpow__()" (the\n' - ' coercion rules would become too complicated).\n' - '\n' - ' Note:\n' - '\n' - ' If the right operand’s type is a subclass of the left ' - 'operand’s\n' - ' type and that subclass provides a different ' - 'implementation of the\n' - ' reflected method for the operation, this method will ' - 'be called\n' - ' before the left operand’s non-reflected method. This ' - 'behavior\n' - ' allows subclasses to override their ancestors’ ' - 'operations.\n' - '\n' - 'object.__iadd__(self, other)\n' - 'object.__isub__(self, other)\n' - 'object.__imul__(self, other)\n' - 'object.__imatmul__(self, other)\n' - 'object.__itruediv__(self, other)\n' - 'object.__ifloordiv__(self, other)\n' - 'object.__imod__(self, other)\n' - 'object.__ipow__(self, other[, modulo])\n' - 'object.__ilshift__(self, other)\n' - 'object.__irshift__(self, other)\n' - 'object.__iand__(self, other)\n' - 'object.__ixor__(self, other)\n' - 'object.__ior__(self, other)\n' - '\n' - ' These methods are called to implement the augmented ' - 'arithmetic\n' - ' assignments ("+=", "-=", "*=", "@=", "/=", "//=", "%=", ' - '"**=",\n' - ' "<<=", ">>=", "&=", "^=", "|="). These methods should ' - 'attempt to\n' - ' do the operation in-place (modifying *self*) and return ' - 'the result\n' - ' (which could be, but does not have to be, *self*). If a ' - 'specific\n' - ' method is not defined, the augmented assignment falls ' - 'back to the\n' - ' normal methods. For instance, if *x* is an instance of ' - 'a class\n' - ' with an "__iadd__()" method, "x += y" is equivalent to ' - '"x =\n' - ' x.__iadd__(y)" . Otherwise, "x.__add__(y)" and ' - '"y.__radd__(x)" are\n' - ' considered, as with the evaluation of "x + y". In ' - 'certain\n' - ' situations, augmented assignment can result in ' - 'unexpected errors\n' - ' (see Why does a_tuple[i] += [‘item’] raise an exception ' - 'when the\n' - ' addition works?), but this behavior is in fact part of ' - 'the data\n' - ' model.\n' - '\n' - 'object.__neg__(self)\n' - 'object.__pos__(self)\n' - 'object.__abs__(self)\n' - 'object.__invert__(self)\n' - '\n' - ' Called to implement the unary arithmetic operations ' - '("-", "+",\n' - ' "abs()" and "~").\n' - '\n' - 'object.__complex__(self)\n' - 'object.__int__(self)\n' - 'object.__float__(self)\n' - '\n' - ' Called to implement the built-in functions "complex()", ' - '"int()" and\n' - ' "float()". Should return a value of the appropriate ' - 'type.\n' - '\n' - 'object.__index__(self)\n' - '\n' - ' Called to implement "operator.index()", and whenever ' - 'Python needs\n' - ' to losslessly convert the numeric object to an integer ' - 'object (such\n' - ' as in slicing, or in the built-in "bin()", "hex()" and ' - '"oct()"\n' - ' functions). Presence of this method indicates that the ' - 'numeric\n' - ' object is an integer type. Must return an integer.\n' - '\n' - ' If "__int__()", "__float__()" and "__complex__()" are ' - 'not defined\n' - ' then corresponding built-in functions "int()", "float()" ' - 'and\n' - ' "complex()" fall back to "__index__()".\n' - '\n' - 'object.__round__(self[, ndigits])\n' - 'object.__trunc__(self)\n' - 'object.__floor__(self)\n' - 'object.__ceil__(self)\n' - '\n' - ' Called to implement the built-in function "round()" and ' - '"math"\n' - ' functions "trunc()", "floor()" and "ceil()". Unless ' - '*ndigits* is\n' - ' passed to "__round__()" all these methods should return ' - 'the value\n' - ' of the object truncated to an "Integral" (typically an ' - '"int").\n' - '\n' - ' The built-in function "int()" falls back to ' - '"__trunc__()" if\n' - ' neither "__int__()" nor "__index__()" is defined.\n', - 'objects': 'Objects, values and types\n' - '*************************\n' - '\n' - '*Objects* are Python’s abstraction for data. All data in a ' - 'Python\n' - 'program is represented by objects or by relations between ' - 'objects. (In\n' - 'a sense, and in conformance to Von Neumann’s model of a “stored\n' - 'program computer”, code is also represented by objects.)\n' - '\n' - 'Every object has an identity, a type and a value. An object’s\n' - '*identity* never changes once it has been created; you may think ' - 'of it\n' - 'as the object’s address in memory. The ‘"is"’ operator compares ' - 'the\n' - 'identity of two objects; the "id()" function returns an integer\n' - 'representing its identity.\n' - '\n' - '**CPython implementation detail:** For CPython, "id(x)" is the ' - 'memory\n' - 'address where "x" is stored.\n' - '\n' - 'An object’s type determines the operations that the object ' - 'supports\n' - '(e.g., “does it have a length?”) and also defines the possible ' - 'values\n' - 'for objects of that type. The "type()" function returns an ' - 'object’s\n' - 'type (which is an object itself). Like its identity, an ' - 'object’s\n' - '*type* is also unchangeable. [1]\n' - '\n' - 'The *value* of some objects can change. Objects whose value can\n' - 'change are said to be *mutable*; objects whose value is ' - 'unchangeable\n' - 'once they are created are called *immutable*. (The value of an\n' - 'immutable container object that contains a reference to a ' - 'mutable\n' - 'object can change when the latter’s value is changed; however ' - 'the\n' - 'container is still considered immutable, because the collection ' - 'of\n' - 'objects it contains cannot be changed. So, immutability is not\n' - 'strictly the same as having an unchangeable value, it is more ' - 'subtle.)\n' - 'An object’s mutability is determined by its type; for instance,\n' - 'numbers, strings and tuples are immutable, while dictionaries ' - 'and\n' - 'lists are mutable.\n' - '\n' - 'Objects are never explicitly destroyed; however, when they ' - 'become\n' - 'unreachable they may be garbage-collected. An implementation is\n' - 'allowed to postpone garbage collection or omit it altogether — it ' - 'is a\n' - 'matter of implementation quality how garbage collection is\n' - 'implemented, as long as no objects are collected that are still\n' - 'reachable.\n' - '\n' - '**CPython implementation detail:** CPython currently uses a ' - 'reference-\n' - 'counting scheme with (optional) delayed detection of cyclically ' - 'linked\n' - 'garbage, which collects most objects as soon as they become\n' - 'unreachable, but is not guaranteed to collect garbage containing\n' - 'circular references. See the documentation of the "gc" module ' - 'for\n' - 'information on controlling the collection of cyclic garbage. ' - 'Other\n' - 'implementations act differently and CPython may change. Do not ' - 'depend\n' - 'on immediate finalization of objects when they become unreachable ' - '(so\n' - 'you should always close files explicitly).\n' - '\n' - 'Note that the use of the implementation’s tracing or debugging\n' - 'facilities may keep objects alive that would normally be ' - 'collectable.\n' - 'Also note that catching an exception with a ‘"try"…"except"’ ' - 'statement\n' - 'may keep objects alive.\n' - '\n' - 'Some objects contain references to “external” resources such as ' - 'open\n' - 'files or windows. It is understood that these resources are ' - 'freed\n' - 'when the object is garbage-collected, but since garbage ' - 'collection is\n' - 'not guaranteed to happen, such objects also provide an explicit ' - 'way to\n' - 'release the external resource, usually a "close()" method. ' - 'Programs\n' - 'are strongly recommended to explicitly close such objects. The\n' - '‘"try"…"finally"’ statement and the ‘"with"’ statement provide\n' - 'convenient ways to do this.\n' - '\n' - 'Some objects contain references to other objects; these are ' - 'called\n' - '*containers*. Examples of containers are tuples, lists and\n' - 'dictionaries. The references are part of a container’s value. ' - 'In\n' - 'most cases, when we talk about the value of a container, we imply ' - 'the\n' - 'values, not the identities of the contained objects; however, ' - 'when we\n' - 'talk about the mutability of a container, only the identities of ' - 'the\n' - 'immediately contained objects are implied. So, if an immutable\n' - 'container (like a tuple) contains a reference to a mutable ' - 'object, its\n' - 'value changes if that mutable object is changed.\n' - '\n' - 'Types affect almost all aspects of object behavior. Even the\n' - 'importance of object identity is affected in some sense: for ' - 'immutable\n' - 'types, operations that compute new values may actually return a\n' - 'reference to any existing object with the same type and value, ' - 'while\n' - 'for mutable objects this is not allowed. E.g., after "a = 1; b = ' - '1",\n' - '"a" and "b" may or may not refer to the same object with the ' - 'value\n' - 'one, depending on the implementation, but after "c = []; d = []", ' - '"c"\n' - 'and "d" are guaranteed to refer to two different, unique, newly\n' - 'created empty lists. (Note that "c = d = []" assigns the same ' - 'object\n' - 'to both "c" and "d".)\n', - 'operator-summary': 'Operator precedence\n' - '*******************\n' - '\n' - 'The following table summarizes the operator precedence ' - 'in Python, from\n' - 'highest precedence (most binding) to lowest precedence ' - '(least\n' - 'binding). Operators in the same box have the same ' - 'precedence. Unless\n' - 'the syntax is explicitly given, operators are binary. ' - 'Operators in\n' - 'the same box group left to right (except for ' - 'exponentiation, which\n' - 'groups from right to left).\n' - '\n' - 'Note that comparisons, membership tests, and identity ' - 'tests, all have\n' - 'the same precedence and have a left-to-right chaining ' - 'feature as\n' - 'described in the Comparisons section.\n' - '\n' - '+-------------------------------------------------+---------------------------------------+\n' - '| Operator | ' - 'Description |\n' - '|=================================================|=======================================|\n' - '| "(expressions...)", "[expressions...]", "{key: | ' - 'Binding or parenthesized expression, |\n' - '| value...}", "{expressions...}" | list ' - 'display, dictionary display, set |\n' - '| | ' - 'display |\n' - '+-------------------------------------------------+---------------------------------------+\n' - '| "x[index]", "x[index:index]", | ' - 'Subscription, slicing, call, |\n' - '| "x(arguments...)", "x.attribute" | ' - 'attribute reference |\n' - '+-------------------------------------------------+---------------------------------------+\n' - '| "await x" | ' - 'Await expression |\n' - '+-------------------------------------------------+---------------------------------------+\n' - '| "**" | ' - 'Exponentiation [5] |\n' - '+-------------------------------------------------+---------------------------------------+\n' - '| "+x", "-x", "~x" | ' - 'Positive, negative, bitwise NOT |\n' - '+-------------------------------------------------+---------------------------------------+\n' - '| "*", "@", "/", "//", "%" | ' - 'Multiplication, matrix |\n' - '| | ' - 'multiplication, division, floor |\n' - '| | ' - 'division, remainder [6] |\n' - '+-------------------------------------------------+---------------------------------------+\n' - '| "+", "-" | ' - 'Addition and subtraction |\n' - '+-------------------------------------------------+---------------------------------------+\n' - '| "<<", ">>" | ' - 'Shifts |\n' - '+-------------------------------------------------+---------------------------------------+\n' - '| "&" | ' - 'Bitwise AND |\n' - '+-------------------------------------------------+---------------------------------------+\n' - '| "^" | ' - 'Bitwise XOR |\n' - '+-------------------------------------------------+---------------------------------------+\n' - '| "|" | ' - 'Bitwise OR |\n' - '+-------------------------------------------------+---------------------------------------+\n' - '| "in", "not in", "is", "is not", "<", "<=", ">", | ' - 'Comparisons, including membership |\n' - '| ">=", "!=", "==" | ' - 'tests and identity tests |\n' - '+-------------------------------------------------+---------------------------------------+\n' - '| "not x" | ' - 'Boolean NOT |\n' - '+-------------------------------------------------+---------------------------------------+\n' - '| "and" | ' - 'Boolean AND |\n' - '+-------------------------------------------------+---------------------------------------+\n' - '| "or" | ' - 'Boolean OR |\n' - '+-------------------------------------------------+---------------------------------------+\n' - '| "if" – "else" | ' - 'Conditional expression |\n' - '+-------------------------------------------------+---------------------------------------+\n' - '| "lambda" | ' - 'Lambda expression |\n' - '+-------------------------------------------------+---------------------------------------+\n' - '| ":=" | ' - 'Assignment expression |\n' - '+-------------------------------------------------+---------------------------------------+\n' - '\n' - '-[ Footnotes ]-\n' - '\n' - '[1] While "abs(x%y) < abs(y)" is true mathematically, ' - 'for floats it\n' - ' may not be true numerically due to roundoff. For ' - 'example, and\n' - ' assuming a platform on which a Python float is an ' - 'IEEE 754 double-\n' - ' precision number, in order that "-1e-100 % 1e100" ' - 'have the same\n' - ' sign as "1e100", the computed result is "-1e-100 + ' - '1e100", which\n' - ' is numerically exactly equal to "1e100". The ' - 'function\n' - ' "math.fmod()" returns a result whose sign matches ' - 'the sign of the\n' - ' first argument instead, and so returns "-1e-100" in ' - 'this case.\n' - ' Which approach is more appropriate depends on the ' - 'application.\n' - '\n' - '[2] If x is very close to an exact integer multiple of ' - 'y, it’s\n' - ' possible for "x//y" to be one larger than ' - '"(x-x%y)//y" due to\n' - ' rounding. In such cases, Python returns the latter ' - 'result, in\n' - ' order to preserve that "divmod(x,y)[0] * y + x % y" ' - 'be very close\n' - ' to "x".\n' - '\n' - '[3] The Unicode standard distinguishes between *code ' - 'points* (e.g.\n' - ' U+0041) and *abstract characters* (e.g. “LATIN ' - 'CAPITAL LETTER A”).\n' - ' While most abstract characters in Unicode are only ' - 'represented\n' - ' using one code point, there is a number of abstract ' - 'characters\n' - ' that can in addition be represented using a sequence ' - 'of more than\n' - ' one code point. For example, the abstract character ' - '“LATIN\n' - ' CAPITAL LETTER C WITH CEDILLA” can be represented as ' - 'a single\n' - ' *precomposed character* at code position U+00C7, or ' - 'as a sequence\n' - ' of a *base character* at code position U+0043 (LATIN ' - 'CAPITAL\n' - ' LETTER C), followed by a *combining character* at ' - 'code position\n' - ' U+0327 (COMBINING CEDILLA).\n' - '\n' - ' The comparison operators on strings compare at the ' - 'level of\n' - ' Unicode code points. This may be counter-intuitive ' - 'to humans. For\n' - ' example, ""\\u00C7" == "\\u0043\\u0327"" is "False", ' - 'even though both\n' - ' strings represent the same abstract character “LATIN ' - 'CAPITAL\n' - ' LETTER C WITH CEDILLA”.\n' - '\n' - ' To compare strings at the level of abstract ' - 'characters (that is,\n' - ' in a way intuitive to humans), use ' - '"unicodedata.normalize()".\n' - '\n' - '[4] Due to automatic garbage-collection, free lists, and ' - 'the dynamic\n' - ' nature of descriptors, you may notice seemingly ' - 'unusual behaviour\n' - ' in certain uses of the "is" operator, like those ' - 'involving\n' - ' comparisons between instance methods, or constants. ' - 'Check their\n' - ' documentation for more info.\n' - '\n' - '[5] The power operator "**" binds less tightly than an ' - 'arithmetic or\n' - ' bitwise unary operator on its right, that is, ' - '"2**-1" is "0.5".\n' - '\n' - '[6] The "%" operator is also used for string formatting; ' - 'the same\n' - ' precedence applies.\n', - 'pass': 'The "pass" statement\n' - '********************\n' - '\n' - ' pass_stmt ::= "pass"\n' - '\n' - '"pass" is a null operation — when it is executed, nothing happens. ' - 'It\n' - 'is useful as a placeholder when a statement is required ' - 'syntactically,\n' - 'but no code needs to be executed, for example:\n' - '\n' - ' def f(arg): pass # a function that does nothing (yet)\n' - '\n' - ' class C: pass # a class with no methods (yet)\n', - 'power': 'The power operator\n' - '******************\n' - '\n' - 'The power operator binds more tightly than unary operators on its\n' - 'left; it binds less tightly than unary operators on its right. ' - 'The\n' - 'syntax is:\n' - '\n' - ' power ::= (await_expr | primary) ["**" u_expr]\n' - '\n' - 'Thus, in an unparenthesized sequence of power and unary operators, ' - 'the\n' - 'operators are evaluated from right to left (this does not ' - 'constrain\n' - 'the evaluation order for the operands): "-1**2" results in "-1".\n' - '\n' - 'The power operator has the same semantics as the built-in "pow()"\n' - 'function, when called with two arguments: it yields its left ' - 'argument\n' - 'raised to the power of its right argument. The numeric arguments ' - 'are\n' - 'first converted to a common type, and the result is of that type.\n' - '\n' - 'For int operands, the result has the same type as the operands ' - 'unless\n' - 'the second argument is negative; in that case, all arguments are\n' - 'converted to float and a float result is delivered. For example,\n' - '"10**2" returns "100", but "10**-2" returns "0.01".\n' - '\n' - 'Raising "0.0" to a negative power results in a ' - '"ZeroDivisionError".\n' - 'Raising a negative number to a fractional power results in a ' - '"complex"\n' - 'number. (In earlier versions it raised a "ValueError".)\n' - '\n' - 'This operation can be customized using the special "__pow__()" ' - 'method.\n', - 'raise': 'The "raise" statement\n' - '*********************\n' - '\n' - ' raise_stmt ::= "raise" [expression ["from" expression]]\n' - '\n' - 'If no expressions are present, "raise" re-raises the exception that ' - 'is\n' - 'currently being handled, which is also known as the *active\n' - 'exception*. If there isn’t currently an active exception, a\n' - '"RuntimeError" exception is raised indicating that this is an ' - 'error.\n' - '\n' - 'Otherwise, "raise" evaluates the first expression as the exception\n' - 'object. It must be either a subclass or an instance of\n' - '"BaseException". If it is a class, the exception instance will be\n' - 'obtained when needed by instantiating the class with no arguments.\n' - '\n' - 'The *type* of the exception is the exception instance’s class, the\n' - '*value* is the instance itself.\n' - '\n' - 'A traceback object is normally created automatically when an ' - 'exception\n' - 'is raised and attached to it as the "__traceback__" attribute, ' - 'which\n' - 'is writable. You can create an exception and set your own traceback ' - 'in\n' - 'one step using the "with_traceback()" exception method (which ' - 'returns\n' - 'the same exception instance, with its traceback set to its ' - 'argument),\n' - 'like so:\n' - '\n' - ' raise Exception("foo occurred").with_traceback(tracebackobj)\n' - '\n' - 'The "from" clause is used for exception chaining: if given, the ' - 'second\n' - '*expression* must be another exception class or instance. If the\n' - 'second expression is an exception instance, it will be attached to ' - 'the\n' - 'raised exception as the "__cause__" attribute (which is writable). ' - 'If\n' - 'the expression is an exception class, the class will be ' - 'instantiated\n' - 'and the resulting exception instance will be attached to the ' - 'raised\n' - 'exception as the "__cause__" attribute. If the raised exception is ' - 'not\n' - 'handled, both exceptions will be printed:\n' - '\n' - ' >>> try:\n' - ' ... print(1 / 0)\n' - ' ... except Exception as exc:\n' - ' ... raise RuntimeError("Something bad happened") from exc\n' - ' ...\n' - ' Traceback (most recent call last):\n' - ' File "<stdin>", line 2, in <module>\n' - ' ZeroDivisionError: division by zero\n' - '\n' - ' The above exception was the direct cause of the following ' - 'exception:\n' - '\n' - ' Traceback (most recent call last):\n' - ' File "<stdin>", line 4, in <module>\n' - ' RuntimeError: Something bad happened\n' - '\n' - 'A similar mechanism works implicitly if a new exception is raised ' - 'when\n' - 'an exception is already being handled. An exception may be ' - 'handled\n' - 'when an "except" or "finally" clause, or a "with" statement, is ' - 'used.\n' - 'The previous exception is then attached as the new exception’s\n' - '"__context__" attribute:\n' - '\n' - ' >>> try:\n' - ' ... print(1 / 0)\n' - ' ... except:\n' - ' ... raise RuntimeError("Something bad happened")\n' - ' ...\n' - ' Traceback (most recent call last):\n' - ' File "<stdin>", line 2, in <module>\n' - ' ZeroDivisionError: division by zero\n' - '\n' - ' During handling of the above exception, another exception ' - 'occurred:\n' - '\n' - ' Traceback (most recent call last):\n' - ' File "<stdin>", line 4, in <module>\n' - ' RuntimeError: Something bad happened\n' - '\n' - 'Exception chaining can be explicitly suppressed by specifying ' - '"None"\n' - 'in the "from" clause:\n' - '\n' - ' >>> try:\n' - ' ... print(1 / 0)\n' - ' ... except:\n' - ' ... raise RuntimeError("Something bad happened") from None\n' - ' ...\n' - ' Traceback (most recent call last):\n' - ' File "<stdin>", line 4, in <module>\n' - ' RuntimeError: Something bad happened\n' - '\n' - 'Additional information on exceptions can be found in section\n' - 'Exceptions, and information about handling exceptions is in ' - 'section\n' - 'The try statement.\n' - '\n' - 'Changed in version 3.3: "None" is now permitted as "Y" in "raise X\n' - 'from Y".\n' - '\n' - 'New in version 3.3: The "__suppress_context__" attribute to ' - 'suppress\n' - 'automatic display of the exception context.\n', - 'return': 'The "return" statement\n' - '**********************\n' - '\n' - ' return_stmt ::= "return" [expression_list]\n' - '\n' - '"return" may only occur syntactically nested in a function ' - 'definition,\n' - 'not within a nested class definition.\n' - '\n' - 'If an expression list is present, it is evaluated, else "None" is\n' - 'substituted.\n' - '\n' - '"return" leaves the current function call with the expression list ' - '(or\n' - '"None") as return value.\n' - '\n' - 'When "return" passes control out of a "try" statement with a ' - '"finally"\n' - 'clause, that "finally" clause is executed before really leaving ' - 'the\n' - 'function.\n' - '\n' - 'In a generator function, the "return" statement indicates that ' - 'the\n' - 'generator is done and will cause "StopIteration" to be raised. ' - 'The\n' - 'returned value (if any) is used as an argument to construct\n' - '"StopIteration" and becomes the "StopIteration.value" attribute.\n' - '\n' - 'In an asynchronous generator function, an empty "return" ' - 'statement\n' - 'indicates that the asynchronous generator is done and will cause\n' - '"StopAsyncIteration" to be raised. A non-empty "return" statement ' - 'is\n' - 'a syntax error in an asynchronous generator function.\n', - 'sequence-types': 'Emulating container types\n' - '*************************\n' - '\n' - 'The following methods can be defined to implement ' - 'container objects.\n' - 'Containers usually are *sequences* (such as "lists" or ' - '"tuples") or\n' - '*mappings* (like "dictionaries"), but can represent other ' - 'containers\n' - 'as well. The first set of methods is used either to ' - 'emulate a\n' - 'sequence or to emulate a mapping; the difference is that ' - 'for a\n' - 'sequence, the allowable keys should be the integers *k* ' - 'for which "0\n' - '<= k < N" where *N* is the length of the sequence, or ' - '"slice" objects,\n' - 'which define a range of items. It is also recommended ' - 'that mappings\n' - 'provide the methods "keys()", "values()", "items()", ' - '"get()",\n' - '"clear()", "setdefault()", "pop()", "popitem()", "copy()", ' - 'and\n' - '"update()" behaving similar to those for Python’s ' - 'standard\n' - '"dictionary" objects. The "collections.abc" module ' - 'provides a\n' - '"MutableMapping" *abstract base class* to help create ' - 'those methods\n' - 'from a base set of "__getitem__()", "__setitem__()", ' - '"__delitem__()",\n' - 'and "keys()". Mutable sequences should provide methods ' - '"append()",\n' - '"count()", "index()", "extend()", "insert()", "pop()", ' - '"remove()",\n' - '"reverse()" and "sort()", like Python standard "list" ' - 'objects.\n' - 'Finally, sequence types should implement addition ' - '(meaning\n' - 'concatenation) and multiplication (meaning repetition) by ' - 'defining the\n' - 'methods "__add__()", "__radd__()", "__iadd__()", ' - '"__mul__()",\n' - '"__rmul__()" and "__imul__()" described below; they should ' - 'not define\n' - 'other numerical operators. It is recommended that both ' - 'mappings and\n' - 'sequences implement the "__contains__()" method to allow ' - 'efficient use\n' - 'of the "in" operator; for mappings, "in" should search the ' - 'mapping’s\n' - 'keys; for sequences, it should search through the values. ' - 'It is\n' - 'further recommended that both mappings and sequences ' - 'implement the\n' - '"__iter__()" method to allow efficient iteration through ' - 'the\n' - 'container; for mappings, "__iter__()" should iterate ' - 'through the\n' - 'object’s keys; for sequences, it should iterate through ' - 'the values.\n' - '\n' - 'object.__len__(self)\n' - '\n' - ' Called to implement the built-in function "len()". ' - 'Should return\n' - ' the length of the object, an integer ">=" 0. Also, an ' - 'object that\n' - ' doesn’t define a "__bool__()" method and whose ' - '"__len__()" method\n' - ' returns zero is considered to be false in a Boolean ' - 'context.\n' - '\n' - ' **CPython implementation detail:** In CPython, the ' - 'length is\n' - ' required to be at most "sys.maxsize". If the length is ' - 'larger than\n' - ' "sys.maxsize" some features (such as "len()") may ' - 'raise\n' - ' "OverflowError". To prevent raising "OverflowError" by ' - 'truth value\n' - ' testing, an object must define a "__bool__()" method.\n' - '\n' - 'object.__length_hint__(self)\n' - '\n' - ' Called to implement "operator.length_hint()". Should ' - 'return an\n' - ' estimated length for the object (which may be greater ' - 'or less than\n' - ' the actual length). The length must be an integer ">=" ' - '0. The\n' - ' return value may also be "NotImplemented", which is ' - 'treated the\n' - ' same as if the "__length_hint__" method didn’t exist at ' - 'all. This\n' - ' method is purely an optimization and is never required ' - 'for\n' - ' correctness.\n' - '\n' - ' New in version 3.4.\n' - '\n' - 'Note:\n' - '\n' - ' Slicing is done exclusively with the following three ' - 'methods. A\n' - ' call like\n' - '\n' - ' a[1:2] = b\n' - '\n' - ' is translated to\n' - '\n' - ' a[slice(1, 2, None)] = b\n' - '\n' - ' and so forth. Missing slice items are always filled in ' - 'with "None".\n' - '\n' - 'object.__getitem__(self, key)\n' - '\n' - ' Called to implement evaluation of "self[key]". For ' - '*sequence*\n' - ' types, the accepted keys should be integers and slice ' - 'objects.\n' - ' Note that the special interpretation of negative ' - 'indexes (if the\n' - ' class wishes to emulate a *sequence* type) is up to ' - 'the\n' - ' "__getitem__()" method. If *key* is of an inappropriate ' - 'type,\n' - ' "TypeError" may be raised; if of a value outside the ' - 'set of indexes\n' - ' for the sequence (after any special interpretation of ' - 'negative\n' - ' values), "IndexError" should be raised. For *mapping* ' - 'types, if\n' - ' *key* is missing (not in the container), "KeyError" ' - 'should be\n' - ' raised.\n' - '\n' - ' Note:\n' - '\n' - ' "for" loops expect that an "IndexError" will be ' - 'raised for\n' - ' illegal indexes to allow proper detection of the end ' - 'of the\n' - ' sequence.\n' - '\n' - ' Note:\n' - '\n' - ' When subscripting a *class*, the special class ' - 'method\n' - ' "__class_getitem__()" may be called instead of ' - '"__getitem__()".\n' - ' See __class_getitem__ versus __getitem__ for more ' - 'details.\n' - '\n' - 'object.__setitem__(self, key, value)\n' - '\n' - ' Called to implement assignment to "self[key]". Same ' - 'note as for\n' - ' "__getitem__()". This should only be implemented for ' - 'mappings if\n' - ' the objects support changes to the values for keys, or ' - 'if new keys\n' - ' can be added, or for sequences if elements can be ' - 'replaced. The\n' - ' same exceptions should be raised for improper *key* ' - 'values as for\n' - ' the "__getitem__()" method.\n' - '\n' - 'object.__delitem__(self, key)\n' - '\n' - ' Called to implement deletion of "self[key]". Same note ' - 'as for\n' - ' "__getitem__()". This should only be implemented for ' - 'mappings if\n' - ' the objects support removal of keys, or for sequences ' - 'if elements\n' - ' can be removed from the sequence. The same exceptions ' - 'should be\n' - ' raised for improper *key* values as for the ' - '"__getitem__()" method.\n' - '\n' - 'object.__missing__(self, key)\n' - '\n' - ' Called by "dict"."__getitem__()" to implement ' - '"self[key]" for dict\n' - ' subclasses when key is not in the dictionary.\n' - '\n' - 'object.__iter__(self)\n' - '\n' - ' This method is called when an *iterator* is required ' - 'for a\n' - ' container. This method should return a new iterator ' - 'object that can\n' - ' iterate over all the objects in the container. For ' - 'mappings, it\n' - ' should iterate over the keys of the container.\n' - '\n' - 'object.__reversed__(self)\n' - '\n' - ' Called (if present) by the "reversed()" built-in to ' - 'implement\n' - ' reverse iteration. It should return a new iterator ' - 'object that\n' - ' iterates over all the objects in the container in ' - 'reverse order.\n' - '\n' - ' If the "__reversed__()" method is not provided, the ' - '"reversed()"\n' - ' built-in will fall back to using the sequence protocol ' - '("__len__()"\n' - ' and "__getitem__()"). Objects that support the ' - 'sequence protocol\n' - ' should only provide "__reversed__()" if they can ' - 'provide an\n' - ' implementation that is more efficient than the one ' - 'provided by\n' - ' "reversed()".\n' - '\n' - 'The membership test operators ("in" and "not in") are ' - 'normally\n' - 'implemented as an iteration through a container. However, ' - 'container\n' - 'objects can supply the following special method with a ' - 'more efficient\n' - 'implementation, which also does not require the object be ' - 'iterable.\n' - '\n' - 'object.__contains__(self, item)\n' - '\n' - ' Called to implement membership test operators. Should ' - 'return true\n' - ' if *item* is in *self*, false otherwise. For mapping ' - 'objects, this\n' - ' should consider the keys of the mapping rather than the ' - 'values or\n' - ' the key-item pairs.\n' - '\n' - ' For objects that don’t define "__contains__()", the ' - 'membership test\n' - ' first tries iteration via "__iter__()", then the old ' - 'sequence\n' - ' iteration protocol via "__getitem__()", see this ' - 'section in the\n' - ' language reference.\n', - 'shifting': 'Shifting operations\n' - '*******************\n' - '\n' - 'The shifting operations have lower priority than the arithmetic\n' - 'operations:\n' - '\n' - ' shift_expr ::= a_expr | shift_expr ("<<" | ">>") a_expr\n' - '\n' - 'These operators accept integers as arguments. They shift the ' - 'first\n' - 'argument to the left or right by the number of bits given by ' - 'the\n' - 'second argument.\n' - '\n' - 'This operation can be customized using the special ' - '"__lshift__()" and\n' - '"__rshift__()" methods.\n' - '\n' - 'A right shift by *n* bits is defined as floor division by ' - '"pow(2,n)".\n' - 'A left shift by *n* bits is defined as multiplication with ' - '"pow(2,n)".\n', - 'slicings': 'Slicings\n' - '********\n' - '\n' - 'A slicing selects a range of items in a sequence object (e.g., ' - 'a\n' - 'string, tuple or list). Slicings may be used as expressions or ' - 'as\n' - 'targets in assignment or "del" statements. The syntax for a ' - 'slicing:\n' - '\n' - ' slicing ::= primary "[" slice_list "]"\n' - ' slice_list ::= slice_item ("," slice_item)* [","]\n' - ' slice_item ::= expression | proper_slice\n' - ' proper_slice ::= [lower_bound] ":" [upper_bound] [ ":" ' - '[stride] ]\n' - ' lower_bound ::= expression\n' - ' upper_bound ::= expression\n' - ' stride ::= expression\n' - '\n' - 'There is ambiguity in the formal syntax here: anything that ' - 'looks like\n' - 'an expression list also looks like a slice list, so any ' - 'subscription\n' - 'can be interpreted as a slicing. Rather than further ' - 'complicating the\n' - 'syntax, this is disambiguated by defining that in this case the\n' - 'interpretation as a subscription takes priority over the\n' - 'interpretation as a slicing (this is the case if the slice list\n' - 'contains no proper slice).\n' - '\n' - 'The semantics for a slicing are as follows. The primary is ' - 'indexed\n' - '(using the same "__getitem__()" method as normal subscription) ' - 'with a\n' - 'key that is constructed from the slice list, as follows. If the ' - 'slice\n' - 'list contains at least one comma, the key is a tuple containing ' - 'the\n' - 'conversion of the slice items; otherwise, the conversion of the ' - 'lone\n' - 'slice item is the key. The conversion of a slice item that is ' - 'an\n' - 'expression is that expression. The conversion of a proper slice ' - 'is a\n' - 'slice object (see section The standard type hierarchy) whose ' - '"start",\n' - '"stop" and "step" attributes are the values of the expressions ' - 'given\n' - 'as lower bound, upper bound and stride, respectively, ' - 'substituting\n' - '"None" for missing expressions.\n', - 'specialattrs': 'Special Attributes\n' - '******************\n' - '\n' - 'The implementation adds a few special read-only attributes ' - 'to several\n' - 'object types, where they are relevant. Some of these are ' - 'not reported\n' - 'by the "dir()" built-in function.\n' - '\n' - 'object.__dict__\n' - '\n' - ' A dictionary or other mapping object used to store an ' - 'object’s\n' - ' (writable) attributes.\n' - '\n' - 'instance.__class__\n' - '\n' - ' The class to which a class instance belongs.\n' - '\n' - 'class.__bases__\n' - '\n' - ' The tuple of base classes of a class object.\n' - '\n' - 'definition.__name__\n' - '\n' - ' The name of the class, function, method, descriptor, or ' - 'generator\n' - ' instance.\n' - '\n' - 'definition.__qualname__\n' - '\n' - ' The *qualified name* of the class, function, method, ' - 'descriptor, or\n' - ' generator instance.\n' - '\n' - ' New in version 3.3.\n' - '\n' - 'class.__mro__\n' - '\n' - ' This attribute is a tuple of classes that are considered ' - 'when\n' - ' looking for base classes during method resolution.\n' - '\n' - 'class.mro()\n' - '\n' - ' This method can be overridden by a metaclass to customize ' - 'the\n' - ' method resolution order for its instances. It is called ' - 'at class\n' - ' instantiation, and its result is stored in "__mro__".\n' - '\n' - 'class.__subclasses__()\n' - '\n' - ' Each class keeps a list of weak references to its ' - 'immediate\n' - ' subclasses. This method returns a list of all those ' - 'references\n' - ' still alive. The list is in definition order. Example:\n' - '\n' - ' >>> int.__subclasses__()\n' - " [<class 'bool'>]\n" - '\n' - '-[ Footnotes ]-\n' - '\n' - '[1] Additional information on these special methods may be ' - 'found in\n' - ' the Python Reference Manual (Basic customization).\n' - '\n' - '[2] As a consequence, the list "[1, 2]" is considered equal ' - 'to "[1.0,\n' - ' 2.0]", and similarly for tuples.\n' - '\n' - '[3] They must have since the parser can’t tell the type of ' - 'the\n' - ' operands.\n' - '\n' - '[4] Cased characters are those with general category ' - 'property being\n' - ' one of “Lu” (Letter, uppercase), “Ll” (Letter, ' - 'lowercase), or “Lt”\n' - ' (Letter, titlecase).\n' - '\n' - '[5] To format only a tuple you should therefore provide a ' - 'singleton\n' - ' tuple whose only element is the tuple to be formatted.\n', - 'specialnames': 'Special method names\n' - '********************\n' - '\n' - 'A class can implement certain operations that are invoked by ' - 'special\n' - 'syntax (such as arithmetic operations or subscripting and ' - 'slicing) by\n' - 'defining methods with special names. This is Python’s ' - 'approach to\n' - '*operator overloading*, allowing classes to define their own ' - 'behavior\n' - 'with respect to language operators. For instance, if a ' - 'class defines\n' - 'a method named "__getitem__()", and "x" is an instance of ' - 'this class,\n' - 'then "x[i]" is roughly equivalent to "type(x).__getitem__(x, ' - 'i)".\n' - 'Except where mentioned, attempts to execute an operation ' - 'raise an\n' - 'exception when no appropriate method is defined (typically\n' - '"AttributeError" or "TypeError").\n' - '\n' - 'Setting a special method to "None" indicates that the ' - 'corresponding\n' - 'operation is not available. For example, if a class sets ' - '"__iter__()"\n' - 'to "None", the class is not iterable, so calling "iter()" on ' - 'its\n' - 'instances will raise a "TypeError" (without falling back to\n' - '"__getitem__()"). [2]\n' - '\n' - 'When implementing a class that emulates any built-in type, ' - 'it is\n' - 'important that the emulation only be implemented to the ' - 'degree that it\n' - 'makes sense for the object being modelled. For example, ' - 'some\n' - 'sequences may work well with retrieval of individual ' - 'elements, but\n' - 'extracting a slice may not make sense. (One example of this ' - 'is the\n' - '"NodeList" interface in the W3C’s Document Object Model.)\n' - '\n' - '\n' - 'Basic customization\n' - '===================\n' - '\n' - 'object.__new__(cls[, ...])\n' - '\n' - ' Called to create a new instance of class *cls*. ' - '"__new__()" is a\n' - ' static method (special-cased so you need not declare it ' - 'as such)\n' - ' that takes the class of which an instance was requested ' - 'as its\n' - ' first argument. The remaining arguments are those passed ' - 'to the\n' - ' object constructor expression (the call to the class). ' - 'The return\n' - ' value of "__new__()" should be the new object instance ' - '(usually an\n' - ' instance of *cls*).\n' - '\n' - ' Typical implementations create a new instance of the ' - 'class by\n' - ' invoking the superclass’s "__new__()" method using\n' - ' "super().__new__(cls[, ...])" with appropriate arguments ' - 'and then\n' - ' modifying the newly-created instance as necessary before ' - 'returning\n' - ' it.\n' - '\n' - ' If "__new__()" is invoked during object construction and ' - 'it returns\n' - ' an instance of *cls*, then the new instance’s ' - '"__init__()" method\n' - ' will be invoked like "__init__(self[, ...])", where ' - '*self* is the\n' - ' new instance and the remaining arguments are the same as ' - 'were\n' - ' passed to the object constructor.\n' - '\n' - ' If "__new__()" does not return an instance of *cls*, then ' - 'the new\n' - ' instance’s "__init__()" method will not be invoked.\n' - '\n' - ' "__new__()" is intended mainly to allow subclasses of ' - 'immutable\n' - ' types (like int, str, or tuple) to customize instance ' - 'creation. It\n' - ' is also commonly overridden in custom metaclasses in ' - 'order to\n' - ' customize class creation.\n' - '\n' - 'object.__init__(self[, ...])\n' - '\n' - ' Called after the instance has been created (by ' - '"__new__()"), but\n' - ' before it is returned to the caller. The arguments are ' - 'those\n' - ' passed to the class constructor expression. If a base ' - 'class has an\n' - ' "__init__()" method, the derived class’s "__init__()" ' - 'method, if\n' - ' any, must explicitly call it to ensure proper ' - 'initialization of the\n' - ' base class part of the instance; for example:\n' - ' "super().__init__([args...])".\n' - '\n' - ' Because "__new__()" and "__init__()" work together in ' - 'constructing\n' - ' objects ("__new__()" to create it, and "__init__()" to ' - 'customize\n' - ' it), no non-"None" value may be returned by "__init__()"; ' - 'doing so\n' - ' will cause a "TypeError" to be raised at runtime.\n' - '\n' - 'object.__del__(self)\n' - '\n' - ' Called when the instance is about to be destroyed. This ' - 'is also\n' - ' called a finalizer or (improperly) a destructor. If a ' - 'base class\n' - ' has a "__del__()" method, the derived class’s "__del__()" ' - 'method,\n' - ' if any, must explicitly call it to ensure proper deletion ' - 'of the\n' - ' base class part of the instance.\n' - '\n' - ' It is possible (though not recommended!) for the ' - '"__del__()" method\n' - ' to postpone destruction of the instance by creating a new ' - 'reference\n' - ' to it. This is called object *resurrection*. It is\n' - ' implementation-dependent whether "__del__()" is called a ' - 'second\n' - ' time when a resurrected object is about to be destroyed; ' - 'the\n' - ' current *CPython* implementation only calls it once.\n' - '\n' - ' It is not guaranteed that "__del__()" methods are called ' - 'for\n' - ' objects that still exist when the interpreter exits.\n' - '\n' - ' Note:\n' - '\n' - ' "del x" doesn’t directly call "x.__del__()" — the ' - 'former\n' - ' decrements the reference count for "x" by one, and the ' - 'latter is\n' - ' only called when "x"’s reference count reaches zero.\n' - '\n' - ' **CPython implementation detail:** It is possible for a ' - 'reference\n' - ' cycle to prevent the reference count of an object from ' - 'going to\n' - ' zero. In this case, the cycle will be later detected and ' - 'deleted\n' - ' by the *cyclic garbage collector*. A common cause of ' - 'reference\n' - ' cycles is when an exception has been caught in a local ' - 'variable.\n' - ' The frame’s locals then reference the exception, which ' - 'references\n' - ' its own traceback, which references the locals of all ' - 'frames caught\n' - ' in the traceback.\n' - '\n' - ' See also: Documentation for the "gc" module.\n' - '\n' - ' Warning:\n' - '\n' - ' Due to the precarious circumstances under which ' - '"__del__()"\n' - ' methods are invoked, exceptions that occur during their ' - 'execution\n' - ' are ignored, and a warning is printed to "sys.stderr" ' - 'instead.\n' - ' In particular:\n' - '\n' - ' * "__del__()" can be invoked when arbitrary code is ' - 'being\n' - ' executed, including from any arbitrary thread. If ' - '"__del__()"\n' - ' needs to take a lock or invoke any other blocking ' - 'resource, it\n' - ' may deadlock as the resource may already be taken by ' - 'the code\n' - ' that gets interrupted to execute "__del__()".\n' - '\n' - ' * "__del__()" can be executed during interpreter ' - 'shutdown. As a\n' - ' consequence, the global variables it needs to access ' - '(including\n' - ' other modules) may already have been deleted or set ' - 'to "None".\n' - ' Python guarantees that globals whose name begins with ' - 'a single\n' - ' underscore are deleted from their module before other ' - 'globals\n' - ' are deleted; if no other references to such globals ' - 'exist, this\n' - ' may help in assuring that imported modules are still ' - 'available\n' - ' at the time when the "__del__()" method is called.\n' - '\n' - 'object.__repr__(self)\n' - '\n' - ' Called by the "repr()" built-in function to compute the ' - '“official”\n' - ' string representation of an object. If at all possible, ' - 'this\n' - ' should look like a valid Python expression that could be ' - 'used to\n' - ' recreate an object with the same value (given an ' - 'appropriate\n' - ' environment). If this is not possible, a string of the ' - 'form\n' - ' "<...some useful description...>" should be returned. The ' - 'return\n' - ' value must be a string object. If a class defines ' - '"__repr__()" but\n' - ' not "__str__()", then "__repr__()" is also used when an ' - '“informal”\n' - ' string representation of instances of that class is ' - 'required.\n' - '\n' - ' This is typically used for debugging, so it is important ' - 'that the\n' - ' representation is information-rich and unambiguous.\n' - '\n' - 'object.__str__(self)\n' - '\n' - ' Called by "str(object)" and the built-in functions ' - '"format()" and\n' - ' "print()" to compute the “informal” or nicely printable ' - 'string\n' - ' representation of an object. The return value must be a ' - 'string\n' - ' object.\n' - '\n' - ' This method differs from "object.__repr__()" in that ' - 'there is no\n' - ' expectation that "__str__()" return a valid Python ' - 'expression: a\n' - ' more convenient or concise representation can be used.\n' - '\n' - ' The default implementation defined by the built-in type ' - '"object"\n' - ' calls "object.__repr__()".\n' - '\n' - 'object.__bytes__(self)\n' - '\n' - ' Called by bytes to compute a byte-string representation ' - 'of an\n' - ' object. This should return a "bytes" object.\n' - '\n' - 'object.__format__(self, format_spec)\n' - '\n' - ' Called by the "format()" built-in function, and by ' - 'extension,\n' - ' evaluation of formatted string literals and the ' - '"str.format()"\n' - ' method, to produce a “formatted” string representation of ' - 'an\n' - ' object. The *format_spec* argument is a string that ' - 'contains a\n' - ' description of the formatting options desired. The ' - 'interpretation\n' - ' of the *format_spec* argument is up to the type ' - 'implementing\n' - ' "__format__()", however most classes will either ' - 'delegate\n' - ' formatting to one of the built-in types, or use a ' - 'similar\n' - ' formatting option syntax.\n' - '\n' - ' See Format Specification Mini-Language for a description ' - 'of the\n' - ' standard formatting syntax.\n' - '\n' - ' The return value must be a string object.\n' - '\n' - ' Changed in version 3.4: The __format__ method of "object" ' - 'itself\n' - ' raises a "TypeError" if passed any non-empty string.\n' - '\n' - ' Changed in version 3.7: "object.__format__(x, \'\')" is ' - 'now\n' - ' equivalent to "str(x)" rather than "format(str(x), ' - '\'\')".\n' - '\n' - 'object.__lt__(self, other)\n' - 'object.__le__(self, other)\n' - 'object.__eq__(self, other)\n' - 'object.__ne__(self, other)\n' - 'object.__gt__(self, other)\n' - 'object.__ge__(self, other)\n' - '\n' - ' These are the so-called “rich comparison” methods. The\n' - ' correspondence between operator symbols and method names ' - 'is as\n' - ' follows: "x<y" calls "x.__lt__(y)", "x<=y" calls ' - '"x.__le__(y)",\n' - ' "x==y" calls "x.__eq__(y)", "x!=y" calls "x.__ne__(y)", ' - '"x>y" calls\n' - ' "x.__gt__(y)", and "x>=y" calls "x.__ge__(y)".\n' - '\n' - ' A rich comparison method may return the singleton ' - '"NotImplemented"\n' - ' if it does not implement the operation for a given pair ' - 'of\n' - ' arguments. By convention, "False" and "True" are returned ' - 'for a\n' - ' successful comparison. However, these methods can return ' - 'any value,\n' - ' so if the comparison operator is used in a Boolean ' - 'context (e.g.,\n' - ' in the condition of an "if" statement), Python will call ' - '"bool()"\n' - ' on the value to determine if the result is true or ' - 'false.\n' - '\n' - ' By default, "object" implements "__eq__()" by using "is", ' - 'returning\n' - ' "NotImplemented" in the case of a false comparison: "True ' - 'if x is y\n' - ' else NotImplemented". For "__ne__()", by default it ' - 'delegates to\n' - ' "__eq__()" and inverts the result unless it is ' - '"NotImplemented".\n' - ' There are no other implied relationships among the ' - 'comparison\n' - ' operators or default implementations; for example, the ' - 'truth of\n' - ' "(x<y or x==y)" does not imply "x<=y". To automatically ' - 'generate\n' - ' ordering operations from a single root operation, see\n' - ' "functools.total_ordering()".\n' - '\n' - ' See the paragraph on "__hash__()" for some important ' - 'notes on\n' - ' creating *hashable* objects which support custom ' - 'comparison\n' - ' operations and are usable as dictionary keys.\n' - '\n' - ' There are no swapped-argument versions of these methods ' - '(to be used\n' - ' when the left argument does not support the operation but ' - 'the right\n' - ' argument does); rather, "__lt__()" and "__gt__()" are ' - 'each other’s\n' - ' reflection, "__le__()" and "__ge__()" are each other’s ' - 'reflection,\n' - ' and "__eq__()" and "__ne__()" are their own reflection. ' - 'If the\n' - ' operands are of different types, and right operand’s type ' - 'is a\n' - ' direct or indirect subclass of the left operand’s type, ' - 'the\n' - ' reflected method of the right operand has priority, ' - 'otherwise the\n' - ' left operand’s method has priority. Virtual subclassing ' - 'is not\n' - ' considered.\n' - '\n' - 'object.__hash__(self)\n' - '\n' - ' Called by built-in function "hash()" and for operations ' - 'on members\n' - ' of hashed collections including "set", "frozenset", and ' - '"dict".\n' - ' The "__hash__()" method should return an integer. The ' - 'only required\n' - ' property is that objects which compare equal have the ' - 'same hash\n' - ' value; it is advised to mix together the hash values of ' - 'the\n' - ' components of the object that also play a part in ' - 'comparison of\n' - ' objects by packing them into a tuple and hashing the ' - 'tuple.\n' - ' Example:\n' - '\n' - ' def __hash__(self):\n' - ' return hash((self.name, self.nick, self.color))\n' - '\n' - ' Note:\n' - '\n' - ' "hash()" truncates the value returned from an object’s ' - 'custom\n' - ' "__hash__()" method to the size of a "Py_ssize_t". ' - 'This is\n' - ' typically 8 bytes on 64-bit builds and 4 bytes on ' - '32-bit builds.\n' - ' If an object’s "__hash__()" must interoperate on ' - 'builds of\n' - ' different bit sizes, be sure to check the width on all ' - 'supported\n' - ' builds. An easy way to do this is with "python -c ' - '"import sys;\n' - ' print(sys.hash_info.width)"".\n' - '\n' - ' If a class does not define an "__eq__()" method it should ' - 'not\n' - ' define a "__hash__()" operation either; if it defines ' - '"__eq__()"\n' - ' but not "__hash__()", its instances will not be usable as ' - 'items in\n' - ' hashable collections. If a class defines mutable objects ' - 'and\n' - ' implements an "__eq__()" method, it should not implement\n' - ' "__hash__()", since the implementation of hashable ' - 'collections\n' - ' requires that a key’s hash value is immutable (if the ' - 'object’s hash\n' - ' value changes, it will be in the wrong hash bucket).\n' - '\n' - ' User-defined classes have "__eq__()" and "__hash__()" ' - 'methods by\n' - ' default; with them, all objects compare unequal (except ' - 'with\n' - ' themselves) and "x.__hash__()" returns an appropriate ' - 'value such\n' - ' that "x == y" implies both that "x is y" and "hash(x) == ' - 'hash(y)".\n' - '\n' - ' A class that overrides "__eq__()" and does not define ' - '"__hash__()"\n' - ' will have its "__hash__()" implicitly set to "None". ' - 'When the\n' - ' "__hash__()" method of a class is "None", instances of ' - 'the class\n' - ' will raise an appropriate "TypeError" when a program ' - 'attempts to\n' - ' retrieve their hash value, and will also be correctly ' - 'identified as\n' - ' unhashable when checking "isinstance(obj,\n' - ' collections.abc.Hashable)".\n' - '\n' - ' If a class that overrides "__eq__()" needs to retain the\n' - ' implementation of "__hash__()" from a parent class, the ' - 'interpreter\n' - ' must be told this explicitly by setting "__hash__ =\n' - ' <ParentClass>.__hash__".\n' - '\n' - ' If a class that does not override "__eq__()" wishes to ' - 'suppress\n' - ' hash support, it should include "__hash__ = None" in the ' - 'class\n' - ' definition. A class which defines its own "__hash__()" ' - 'that\n' - ' explicitly raises a "TypeError" would be incorrectly ' - 'identified as\n' - ' hashable by an "isinstance(obj, ' - 'collections.abc.Hashable)" call.\n' - '\n' - ' Note:\n' - '\n' - ' By default, the "__hash__()" values of str and bytes ' - 'objects are\n' - ' “salted” with an unpredictable random value. Although ' - 'they\n' - ' remain constant within an individual Python process, ' - 'they are not\n' - ' predictable between repeated invocations of Python.This ' - 'is\n' - ' intended to provide protection against a ' - 'denial-of-service caused\n' - ' by carefully-chosen inputs that exploit the worst case\n' - ' performance of a dict insertion, O(n^2) complexity. ' - 'See\n' - ' http://www.ocert.org/advisories/ocert-2011-003.html ' - 'for\n' - ' details.Changing hash values affects the iteration ' - 'order of sets.\n' - ' Python has never made guarantees about this ordering ' - '(and it\n' - ' typically varies between 32-bit and 64-bit builds).See ' - 'also\n' - ' "PYTHONHASHSEED".\n' - '\n' - ' Changed in version 3.3: Hash randomization is enabled by ' - 'default.\n' - '\n' - 'object.__bool__(self)\n' - '\n' - ' Called to implement truth value testing and the built-in ' - 'operation\n' - ' "bool()"; should return "False" or "True". When this ' - 'method is not\n' - ' defined, "__len__()" is called, if it is defined, and the ' - 'object is\n' - ' considered true if its result is nonzero. If a class ' - 'defines\n' - ' neither "__len__()" nor "__bool__()", all its instances ' - 'are\n' - ' considered true.\n' - '\n' - '\n' - 'Customizing attribute access\n' - '============================\n' - '\n' - 'The following methods can be defined to customize the ' - 'meaning of\n' - 'attribute access (use of, assignment to, or deletion of ' - '"x.name") for\n' - 'class instances.\n' - '\n' - 'object.__getattr__(self, name)\n' - '\n' - ' Called when the default attribute access fails with an\n' - ' "AttributeError" (either "__getattribute__()" raises an\n' - ' "AttributeError" because *name* is not an instance ' - 'attribute or an\n' - ' attribute in the class tree for "self"; or "__get__()" of ' - 'a *name*\n' - ' property raises "AttributeError"). This method should ' - 'either\n' - ' return the (computed) attribute value or raise an ' - '"AttributeError"\n' - ' exception.\n' - '\n' - ' Note that if the attribute is found through the normal ' - 'mechanism,\n' - ' "__getattr__()" is not called. (This is an intentional ' - 'asymmetry\n' - ' between "__getattr__()" and "__setattr__()".) This is ' - 'done both for\n' - ' efficiency reasons and because otherwise "__getattr__()" ' - 'would have\n' - ' no way to access other attributes of the instance. Note ' - 'that at\n' - ' least for instance variables, you can fake total control ' - 'by not\n' - ' inserting any values in the instance attribute dictionary ' - '(but\n' - ' instead inserting them in another object). See the\n' - ' "__getattribute__()" method below for a way to actually ' - 'get total\n' - ' control over attribute access.\n' - '\n' - 'object.__getattribute__(self, name)\n' - '\n' - ' Called unconditionally to implement attribute accesses ' - 'for\n' - ' instances of the class. If the class also defines ' - '"__getattr__()",\n' - ' the latter will not be called unless "__getattribute__()" ' - 'either\n' - ' calls it explicitly or raises an "AttributeError". This ' - 'method\n' - ' should return the (computed) attribute value or raise an\n' - ' "AttributeError" exception. In order to avoid infinite ' - 'recursion in\n' - ' this method, its implementation should always call the ' - 'base class\n' - ' method with the same name to access any attributes it ' - 'needs, for\n' - ' example, "object.__getattribute__(self, name)".\n' - '\n' - ' Note:\n' - '\n' - ' This method may still be bypassed when looking up ' - 'special methods\n' - ' as the result of implicit invocation via language ' - 'syntax or\n' - ' built-in functions. See Special method lookup.\n' - '\n' - ' For certain sensitive attribute accesses, raises an ' - 'auditing event\n' - ' "object.__getattr__" with arguments "obj" and "name".\n' - '\n' - 'object.__setattr__(self, name, value)\n' - '\n' - ' Called when an attribute assignment is attempted. This ' - 'is called\n' - ' instead of the normal mechanism (i.e. store the value in ' - 'the\n' - ' instance dictionary). *name* is the attribute name, ' - '*value* is the\n' - ' value to be assigned to it.\n' - '\n' - ' If "__setattr__()" wants to assign to an instance ' - 'attribute, it\n' - ' should call the base class method with the same name, for ' - 'example,\n' - ' "object.__setattr__(self, name, value)".\n' - '\n' - ' For certain sensitive attribute assignments, raises an ' - 'auditing\n' - ' event "object.__setattr__" with arguments "obj", "name", ' - '"value".\n' - '\n' - 'object.__delattr__(self, name)\n' - '\n' - ' Like "__setattr__()" but for attribute deletion instead ' - 'of\n' - ' assignment. This should only be implemented if "del ' - 'obj.name" is\n' - ' meaningful for the object.\n' - '\n' - ' For certain sensitive attribute deletions, raises an ' - 'auditing event\n' - ' "object.__delattr__" with arguments "obj" and "name".\n' - '\n' - 'object.__dir__(self)\n' - '\n' - ' Called when "dir()" is called on the object. A sequence ' - 'must be\n' - ' returned. "dir()" converts the returned sequence to a ' - 'list and\n' - ' sorts it.\n' - '\n' - '\n' - 'Customizing module attribute access\n' - '-----------------------------------\n' - '\n' - 'Special names "__getattr__" and "__dir__" can be also used ' - 'to\n' - 'customize access to module attributes. The "__getattr__" ' - 'function at\n' - 'the module level should accept one argument which is the ' - 'name of an\n' - 'attribute and return the computed value or raise an ' - '"AttributeError".\n' - 'If an attribute is not found on a module object through the ' - 'normal\n' - 'lookup, i.e. "object.__getattribute__()", then "__getattr__" ' - 'is\n' - 'searched in the module "__dict__" before raising an ' - '"AttributeError".\n' - 'If found, it is called with the attribute name and the ' - 'result is\n' - 'returned.\n' - '\n' - 'The "__dir__" function should accept no arguments, and ' - 'return a\n' - 'sequence of strings that represents the names accessible on ' - 'module. If\n' - 'present, this function overrides the standard "dir()" search ' - 'on a\n' - 'module.\n' - '\n' - 'For a more fine grained customization of the module behavior ' - '(setting\n' - 'attributes, properties, etc.), one can set the "__class__" ' - 'attribute\n' - 'of a module object to a subclass of "types.ModuleType". For ' - 'example:\n' - '\n' - ' import sys\n' - ' from types import ModuleType\n' - '\n' - ' class VerboseModule(ModuleType):\n' - ' def __repr__(self):\n' - " return f'Verbose {self.__name__}'\n" - '\n' - ' def __setattr__(self, attr, value):\n' - " print(f'Setting {attr}...')\n" - ' super().__setattr__(attr, value)\n' - '\n' - ' sys.modules[__name__].__class__ = VerboseModule\n' - '\n' - 'Note:\n' - '\n' - ' Defining module "__getattr__" and setting module ' - '"__class__" only\n' - ' affect lookups made using the attribute access syntax – ' - 'directly\n' - ' accessing the module globals (whether by code within the ' - 'module, or\n' - ' via a reference to the module’s globals dictionary) is ' - 'unaffected.\n' - '\n' - 'Changed in version 3.5: "__class__" module attribute is now ' - 'writable.\n' - '\n' - 'New in version 3.7: "__getattr__" and "__dir__" module ' - 'attributes.\n' - '\n' - 'See also:\n' - '\n' - ' **PEP 562** - Module __getattr__ and __dir__\n' - ' Describes the "__getattr__" and "__dir__" functions on ' - 'modules.\n' - '\n' - '\n' - 'Implementing Descriptors\n' - '------------------------\n' - '\n' - 'The following methods only apply when an instance of the ' - 'class\n' - 'containing the method (a so-called *descriptor* class) ' - 'appears in an\n' - '*owner* class (the descriptor must be in either the owner’s ' - 'class\n' - 'dictionary or in the class dictionary for one of its ' - 'parents). In the\n' - 'examples below, “the attribute” refers to the attribute ' - 'whose name is\n' - 'the key of the property in the owner class’ "__dict__".\n' - '\n' - 'object.__get__(self, instance, owner=None)\n' - '\n' - ' Called to get the attribute of the owner class (class ' - 'attribute\n' - ' access) or of an instance of that class (instance ' - 'attribute\n' - ' access). The optional *owner* argument is the owner ' - 'class, while\n' - ' *instance* is the instance that the attribute was ' - 'accessed through,\n' - ' or "None" when the attribute is accessed through the ' - '*owner*.\n' - '\n' - ' This method should return the computed attribute value or ' - 'raise an\n' - ' "AttributeError" exception.\n' - '\n' - ' **PEP 252** specifies that "__get__()" is callable with ' - 'one or two\n' - ' arguments. Python’s own built-in descriptors support ' - 'this\n' - ' specification; however, it is likely that some ' - 'third-party tools\n' - ' have descriptors that require both arguments. Python’s ' - 'own\n' - ' "__getattribute__()" implementation always passes in both ' - 'arguments\n' - ' whether they are required or not.\n' - '\n' - 'object.__set__(self, instance, value)\n' - '\n' - ' Called to set the attribute on an instance *instance* of ' - 'the owner\n' - ' class to a new value, *value*.\n' - '\n' - ' Note, adding "__set__()" or "__delete__()" changes the ' - 'kind of\n' - ' descriptor to a “data descriptor”. See Invoking ' - 'Descriptors for\n' - ' more details.\n' - '\n' - 'object.__delete__(self, instance)\n' - '\n' - ' Called to delete the attribute on an instance *instance* ' - 'of the\n' - ' owner class.\n' - '\n' - 'The attribute "__objclass__" is interpreted by the "inspect" ' - 'module as\n' - 'specifying the class where this object was defined (setting ' - 'this\n' - 'appropriately can assist in runtime introspection of dynamic ' - 'class\n' - 'attributes). For callables, it may indicate that an instance ' - 'of the\n' - 'given type (or a subclass) is expected or required as the ' - 'first\n' - 'positional argument (for example, CPython sets this ' - 'attribute for\n' - 'unbound methods that are implemented in C).\n' - '\n' - '\n' - 'Invoking Descriptors\n' - '--------------------\n' - '\n' - 'In general, a descriptor is an object attribute with ' - '“binding\n' - 'behavior”, one whose attribute access has been overridden by ' - 'methods\n' - 'in the descriptor protocol: "__get__()", "__set__()", and\n' - '"__delete__()". If any of those methods are defined for an ' - 'object, it\n' - 'is said to be a descriptor.\n' - '\n' - 'The default behavior for attribute access is to get, set, or ' - 'delete\n' - 'the attribute from an object’s dictionary. For instance, ' - '"a.x" has a\n' - 'lookup chain starting with "a.__dict__[\'x\']", then\n' - '"type(a).__dict__[\'x\']", and continuing through the base ' - 'classes of\n' - '"type(a)" excluding metaclasses.\n' - '\n' - 'However, if the looked-up value is an object defining one of ' - 'the\n' - 'descriptor methods, then Python may override the default ' - 'behavior and\n' - 'invoke the descriptor method instead. Where this occurs in ' - 'the\n' - 'precedence chain depends on which descriptor methods were ' - 'defined and\n' - 'how they were called.\n' - '\n' - 'The starting point for descriptor invocation is a binding, ' - '"a.x". How\n' - 'the arguments are assembled depends on "a":\n' - '\n' - 'Direct Call\n' - ' The simplest and least common call is when user code ' - 'directly\n' - ' invokes a descriptor method: "x.__get__(a)".\n' - '\n' - 'Instance Binding\n' - ' If binding to an object instance, "a.x" is transformed ' - 'into the\n' - ' call: "type(a).__dict__[\'x\'].__get__(a, type(a))".\n' - '\n' - 'Class Binding\n' - ' If binding to a class, "A.x" is transformed into the ' - 'call:\n' - ' "A.__dict__[\'x\'].__get__(None, A)".\n' - '\n' - 'Super Binding\n' - ' If "a" is an instance of "super", then the binding ' - '"super(B,\n' - ' obj).m()" searches "obj.__class__.__mro__" for the base ' - 'class "A"\n' - ' immediately following "B" and then invokes the descriptor ' - 'with the\n' - ' call: "A.__dict__[\'m\'].__get__(obj, obj.__class__)".\n' - '\n' - 'For instance bindings, the precedence of descriptor ' - 'invocation depends\n' - 'on which descriptor methods are defined. A descriptor can ' - 'define any\n' - 'combination of "__get__()", "__set__()" and "__delete__()". ' - 'If it\n' - 'does not define "__get__()", then accessing the attribute ' - 'will return\n' - 'the descriptor object itself unless there is a value in the ' - 'object’s\n' - 'instance dictionary. If the descriptor defines "__set__()" ' - 'and/or\n' - '"__delete__()", it is a data descriptor; if it defines ' - 'neither, it is\n' - 'a non-data descriptor. Normally, data descriptors define ' - 'both\n' - '"__get__()" and "__set__()", while non-data descriptors have ' - 'just the\n' - '"__get__()" method. Data descriptors with "__get__()" and ' - '"__set__()"\n' - '(and/or "__delete__()") defined always override a ' - 'redefinition in an\n' - 'instance dictionary. In contrast, non-data descriptors can ' - 'be\n' - 'overridden by instances.\n' - '\n' - 'Python methods (including those decorated with ' - '"@staticmethod" and\n' - '"@classmethod") are implemented as non-data descriptors. ' - 'Accordingly,\n' - 'instances can redefine and override methods. This allows ' - 'individual\n' - 'instances to acquire behaviors that differ from other ' - 'instances of the\n' - 'same class.\n' - '\n' - 'The "property()" function is implemented as a data ' - 'descriptor.\n' - 'Accordingly, instances cannot override the behavior of a ' - 'property.\n' - '\n' - '\n' - '__slots__\n' - '---------\n' - '\n' - '*__slots__* allow us to explicitly declare data members ' - '(like\n' - 'properties) and deny the creation of "__dict__" and ' - '*__weakref__*\n' - '(unless explicitly declared in *__slots__* or available in a ' - 'parent.)\n' - '\n' - 'The space saved over using "__dict__" can be significant. ' - 'Attribute\n' - 'lookup speed can be significantly improved as well.\n' - '\n' - 'object.__slots__\n' - '\n' - ' This class variable can be assigned a string, iterable, ' - 'or sequence\n' - ' of strings with variable names used by instances. ' - '*__slots__*\n' - ' reserves space for the declared variables and prevents ' - 'the\n' - ' automatic creation of "__dict__" and *__weakref__* for ' - 'each\n' - ' instance.\n' - '\n' - '\n' - 'Notes on using *__slots__*\n' - '~~~~~~~~~~~~~~~~~~~~~~~~~~\n' - '\n' - '* When inheriting from a class without *__slots__*, the ' - '"__dict__" and\n' - ' *__weakref__* attribute of the instances will always be ' - 'accessible.\n' - '\n' - '* Without a "__dict__" variable, instances cannot be ' - 'assigned new\n' - ' variables not listed in the *__slots__* definition. ' - 'Attempts to\n' - ' assign to an unlisted variable name raises ' - '"AttributeError". If\n' - ' dynamic assignment of new variables is desired, then add\n' - ' "\'__dict__\'" to the sequence of strings in the ' - '*__slots__*\n' - ' declaration.\n' - '\n' - '* Without a *__weakref__* variable for each instance, ' - 'classes defining\n' - ' *__slots__* do not support "weak references" to its ' - 'instances. If\n' - ' weak reference support is needed, then add ' - '"\'__weakref__\'" to the\n' - ' sequence of strings in the *__slots__* declaration.\n' - '\n' - '* *__slots__* are implemented at the class level by ' - 'creating\n' - ' descriptors for each variable name. As a result, class ' - 'attributes\n' - ' cannot be used to set default values for instance ' - 'variables defined\n' - ' by *__slots__*; otherwise, the class attribute would ' - 'overwrite the\n' - ' descriptor assignment.\n' - '\n' - '* The action of a *__slots__* declaration is not limited to ' - 'the class\n' - ' where it is defined. *__slots__* declared in parents are ' - 'available\n' - ' in child classes. However, child subclasses will get a ' - '"__dict__"\n' - ' and *__weakref__* unless they also define *__slots__* ' - '(which should\n' - ' only contain names of any *additional* slots).\n' - '\n' - '* If a class defines a slot also defined in a base class, ' - 'the instance\n' - ' variable defined by the base class slot is inaccessible ' - '(except by\n' - ' retrieving its descriptor directly from the base class). ' - 'This\n' - ' renders the meaning of the program undefined. In the ' - 'future, a\n' - ' check may be added to prevent this.\n' - '\n' - '* Nonempty *__slots__* does not work for classes derived ' - 'from\n' - ' “variable-length” built-in types such as "int", "bytes" ' - 'and "tuple".\n' - '\n' - '* Any non-string *iterable* may be assigned to *__slots__*.\n' - '\n' - '* If a "dictionary" is used to assign *__slots__*, the ' - 'dictionary keys\n' - ' will be used as the slot names. The values of the ' - 'dictionary can be\n' - ' used to provide per-attribute docstrings that will be ' - 'recognised by\n' - ' "inspect.getdoc()" and displayed in the output of ' - '"help()".\n' - '\n' - '* "__class__" assignment works only if both classes have the ' - 'same\n' - ' *__slots__*.\n' - '\n' - '* Multiple inheritance with multiple slotted parent classes ' - 'can be\n' - ' used, but only one parent is allowed to have attributes ' - 'created by\n' - ' slots (the other bases must have empty slot layouts) - ' - 'violations\n' - ' raise "TypeError".\n' - '\n' - '* If an *iterator* is used for *__slots__* then a ' - '*descriptor* is\n' - ' created for each of the iterator’s values. However, the ' - '*__slots__*\n' - ' attribute will be an empty iterator.\n' - '\n' - '\n' - 'Customizing class creation\n' - '==========================\n' - '\n' - 'Whenever a class inherits from another class, ' - '"__init_subclass__()" is\n' - 'called on the parent class. This way, it is possible to ' - 'write classes\n' - 'which change the behavior of subclasses. This is closely ' - 'related to\n' - 'class decorators, but where class decorators only affect the ' - 'specific\n' - 'class they’re applied to, "__init_subclass__" solely applies ' - 'to future\n' - 'subclasses of the class defining the method.\n' - '\n' - 'classmethod object.__init_subclass__(cls)\n' - '\n' - ' This method is called whenever the containing class is ' - 'subclassed.\n' - ' *cls* is then the new subclass. If defined as a normal ' - 'instance\n' - ' method, this method is implicitly converted to a class ' - 'method.\n' - '\n' - ' Keyword arguments which are given to a new class are ' - 'passed to the\n' - ' parent’s class "__init_subclass__". For compatibility ' - 'with other\n' - ' classes using "__init_subclass__", one should take out ' - 'the needed\n' - ' keyword arguments and pass the others over to the base ' - 'class, as\n' - ' in:\n' - '\n' - ' class Philosopher:\n' - ' def __init_subclass__(cls, /, default_name, ' - '**kwargs):\n' - ' super().__init_subclass__(**kwargs)\n' - ' cls.default_name = default_name\n' - '\n' - ' class AustralianPhilosopher(Philosopher, ' - 'default_name="Bruce"):\n' - ' pass\n' - '\n' - ' The default implementation "object.__init_subclass__" ' - 'does nothing,\n' - ' but raises an error if it is called with any arguments.\n' - '\n' - ' Note:\n' - '\n' - ' The metaclass hint "metaclass" is consumed by the rest ' - 'of the\n' - ' type machinery, and is never passed to ' - '"__init_subclass__"\n' - ' implementations. The actual metaclass (rather than the ' - 'explicit\n' - ' hint) can be accessed as "type(cls)".\n' - '\n' - ' New in version 3.6.\n' - '\n' - 'When a class is created, "type.__new__()" scans the class ' - 'variables\n' - 'and makes callbacks to those with a "__set_name__()" hook.\n' - '\n' - 'object.__set_name__(self, owner, name)\n' - '\n' - ' Automatically called at the time the owning class *owner* ' - 'is\n' - ' created. The object has been assigned to *name* in that ' - 'class:\n' - '\n' - ' class A:\n' - ' x = C() # Automatically calls: x.__set_name__(A, ' - "'x')\n" - '\n' - ' If the class variable is assigned after the class is ' - 'created,\n' - ' "__set_name__()" will not be called automatically. If ' - 'needed,\n' - ' "__set_name__()" can be called directly:\n' - '\n' - ' class A:\n' - ' pass\n' - '\n' - ' c = C()\n' - ' A.x = c # The hook is not called\n' - " c.__set_name__(A, 'x') # Manually invoke the hook\n" - '\n' - ' See Creating the class object for more details.\n' - '\n' - ' New in version 3.6.\n' - '\n' - '\n' - 'Metaclasses\n' - '-----------\n' - '\n' - 'By default, classes are constructed using "type()". The ' - 'class body is\n' - 'executed in a new namespace and the class name is bound ' - 'locally to the\n' - 'result of "type(name, bases, namespace)".\n' - '\n' - 'The class creation process can be customized by passing the\n' - '"metaclass" keyword argument in the class definition line, ' - 'or by\n' - 'inheriting from an existing class that included such an ' - 'argument. In\n' - 'the following example, both "MyClass" and "MySubclass" are ' - 'instances\n' - 'of "Meta":\n' - '\n' - ' class Meta(type):\n' - ' pass\n' - '\n' - ' class MyClass(metaclass=Meta):\n' - ' pass\n' - '\n' - ' class MySubclass(MyClass):\n' - ' pass\n' - '\n' - 'Any other keyword arguments that are specified in the class ' - 'definition\n' - 'are passed through to all metaclass operations described ' - 'below.\n' - '\n' - 'When a class definition is executed, the following steps ' - 'occur:\n' - '\n' - '* MRO entries are resolved;\n' - '\n' - '* the appropriate metaclass is determined;\n' - '\n' - '* the class namespace is prepared;\n' - '\n' - '* the class body is executed;\n' - '\n' - '* the class object is created.\n' - '\n' - '\n' - 'Resolving MRO entries\n' - '---------------------\n' - '\n' - 'If a base that appears in class definition is not an ' - 'instance of\n' - '"type", then an "__mro_entries__" method is searched on it. ' - 'If found,\n' - 'it is called with the original bases tuple. This method must ' - 'return a\n' - 'tuple of classes that will be used instead of this base. The ' - 'tuple may\n' - 'be empty, in such case the original base is ignored.\n' - '\n' - 'See also:\n' - '\n' - ' **PEP 560** - Core support for typing module and generic ' - 'types\n' - '\n' - '\n' - 'Determining the appropriate metaclass\n' - '-------------------------------------\n' - '\n' - 'The appropriate metaclass for a class definition is ' - 'determined as\n' - 'follows:\n' - '\n' - '* if no bases and no explicit metaclass are given, then ' - '"type()" is\n' - ' used;\n' - '\n' - '* if an explicit metaclass is given and it is *not* an ' - 'instance of\n' - ' "type()", then it is used directly as the metaclass;\n' - '\n' - '* if an instance of "type()" is given as the explicit ' - 'metaclass, or\n' - ' bases are defined, then the most derived metaclass is ' - 'used.\n' - '\n' - 'The most derived metaclass is selected from the explicitly ' - 'specified\n' - 'metaclass (if any) and the metaclasses (i.e. "type(cls)") of ' - 'all\n' - 'specified base classes. The most derived metaclass is one ' - 'which is a\n' - 'subtype of *all* of these candidate metaclasses. If none of ' - 'the\n' - 'candidate metaclasses meets that criterion, then the class ' - 'definition\n' - 'will fail with "TypeError".\n' - '\n' - '\n' - 'Preparing the class namespace\n' - '-----------------------------\n' - '\n' - 'Once the appropriate metaclass has been identified, then the ' - 'class\n' - 'namespace is prepared. If the metaclass has a "__prepare__" ' - 'attribute,\n' - 'it is called as "namespace = metaclass.__prepare__(name, ' - 'bases,\n' - '**kwds)" (where the additional keyword arguments, if any, ' - 'come from\n' - 'the class definition). The "__prepare__" method should be ' - 'implemented\n' - 'as a "classmethod". The namespace returned by "__prepare__" ' - 'is passed\n' - 'in to "__new__", but when the final class object is created ' - 'the\n' - 'namespace is copied into a new "dict".\n' - '\n' - 'If the metaclass has no "__prepare__" attribute, then the ' - 'class\n' - 'namespace is initialised as an empty ordered mapping.\n' - '\n' - 'See also:\n' - '\n' - ' **PEP 3115** - Metaclasses in Python 3000\n' - ' Introduced the "__prepare__" namespace hook\n' - '\n' - '\n' - 'Executing the class body\n' - '------------------------\n' - '\n' - 'The class body is executed (approximately) as "exec(body, ' - 'globals(),\n' - 'namespace)". The key difference from a normal call to ' - '"exec()" is that\n' - 'lexical scoping allows the class body (including any ' - 'methods) to\n' - 'reference names from the current and outer scopes when the ' - 'class\n' - 'definition occurs inside a function.\n' - '\n' - 'However, even when the class definition occurs inside the ' - 'function,\n' - 'methods defined inside the class still cannot see names ' - 'defined at the\n' - 'class scope. Class variables must be accessed through the ' - 'first\n' - 'parameter of instance or class methods, or through the ' - 'implicit\n' - 'lexically scoped "__class__" reference described in the next ' - 'section.\n' - '\n' - '\n' - 'Creating the class object\n' - '-------------------------\n' - '\n' - 'Once the class namespace has been populated by executing the ' - 'class\n' - 'body, the class object is created by calling ' - '"metaclass(name, bases,\n' - 'namespace, **kwds)" (the additional keywords passed here are ' - 'the same\n' - 'as those passed to "__prepare__").\n' - '\n' - 'This class object is the one that will be referenced by the ' - 'zero-\n' - 'argument form of "super()". "__class__" is an implicit ' - 'closure\n' - 'reference created by the compiler if any methods in a class ' - 'body refer\n' - 'to either "__class__" or "super". This allows the zero ' - 'argument form\n' - 'of "super()" to correctly identify the class being defined ' - 'based on\n' - 'lexical scoping, while the class or instance that was used ' - 'to make the\n' - 'current call is identified based on the first argument ' - 'passed to the\n' - 'method.\n' - '\n' - '**CPython implementation detail:** In CPython 3.6 and later, ' - 'the\n' - '"__class__" cell is passed to the metaclass as a ' - '"__classcell__" entry\n' - 'in the class namespace. If present, this must be propagated ' - 'up to the\n' - '"type.__new__" call in order for the class to be ' - 'initialised\n' - 'correctly. Failing to do so will result in a "RuntimeError" ' - 'in Python\n' - '3.8.\n' - '\n' - 'When using the default metaclass "type", or any metaclass ' - 'that\n' - 'ultimately calls "type.__new__", the following additional\n' - 'customization steps are invoked after creating the class ' - 'object:\n' - '\n' - '1. The "type.__new__" method collects all of the attributes ' - 'in the\n' - ' class namespace that define a "__set_name__()" method;\n' - '\n' - '2. Those "__set_name__" methods are called with the class ' - 'being\n' - ' defined and the assigned name of that particular ' - 'attribute;\n' - '\n' - '3. The "__init_subclass__()" hook is called on the immediate ' - 'parent of\n' - ' the new class in its method resolution order.\n' - '\n' - 'After the class object is created, it is passed to the ' - 'class\n' - 'decorators included in the class definition (if any) and the ' - 'resulting\n' - 'object is bound in the local namespace as the defined ' - 'class.\n' - '\n' - 'When a new class is created by "type.__new__", the object ' - 'provided as\n' - 'the namespace parameter is copied to a new ordered mapping ' - 'and the\n' - 'original object is discarded. The new copy is wrapped in a ' - 'read-only\n' - 'proxy, which becomes the "__dict__" attribute of the class ' - 'object.\n' - '\n' - 'See also:\n' - '\n' - ' **PEP 3135** - New super\n' - ' Describes the implicit "__class__" closure reference\n' - '\n' - '\n' - 'Uses for metaclasses\n' - '--------------------\n' - '\n' - 'The potential uses for metaclasses are boundless. Some ideas ' - 'that have\n' - 'been explored include enum, logging, interface checking, ' - 'automatic\n' - 'delegation, automatic property creation, proxies, ' - 'frameworks, and\n' - 'automatic resource locking/synchronization.\n' - '\n' - '\n' - 'Customizing instance and subclass checks\n' - '========================================\n' - '\n' - 'The following methods are used to override the default ' - 'behavior of the\n' - '"isinstance()" and "issubclass()" built-in functions.\n' - '\n' - 'In particular, the metaclass "abc.ABCMeta" implements these ' - 'methods in\n' - 'order to allow the addition of Abstract Base Classes (ABCs) ' - 'as\n' - '“virtual base classes” to any class or type (including ' - 'built-in\n' - 'types), including other ABCs.\n' - '\n' - 'class.__instancecheck__(self, instance)\n' - '\n' - ' Return true if *instance* should be considered a (direct ' - 'or\n' - ' indirect) instance of *class*. If defined, called to ' - 'implement\n' - ' "isinstance(instance, class)".\n' - '\n' - 'class.__subclasscheck__(self, subclass)\n' - '\n' - ' Return true if *subclass* should be considered a (direct ' - 'or\n' - ' indirect) subclass of *class*. If defined, called to ' - 'implement\n' - ' "issubclass(subclass, class)".\n' - '\n' - 'Note that these methods are looked up on the type ' - '(metaclass) of a\n' - 'class. They cannot be defined as class methods in the ' - 'actual class.\n' - 'This is consistent with the lookup of special methods that ' - 'are called\n' - 'on instances, only in this case the instance is itself a ' - 'class.\n' - '\n' - 'See also:\n' - '\n' - ' **PEP 3119** - Introducing Abstract Base Classes\n' - ' Includes the specification for customizing ' - '"isinstance()" and\n' - ' "issubclass()" behavior through "__instancecheck__()" ' - 'and\n' - ' "__subclasscheck__()", with motivation for this ' - 'functionality in\n' - ' the context of adding Abstract Base Classes (see the ' - '"abc"\n' - ' module) to the language.\n' - '\n' - '\n' - 'Emulating generic types\n' - '=======================\n' - '\n' - 'When using *type annotations*, it is often useful to ' - '*parameterize* a\n' - '*generic type* using Python’s square-brackets notation. For ' - 'example,\n' - 'the annotation "list[int]" might be used to signify a "list" ' - 'in which\n' - 'all the elements are of type "int".\n' - '\n' - 'See also:\n' - '\n' - ' **PEP 484** - Type Hints\n' - ' Introducing Python’s framework for type annotations\n' - '\n' - ' Generic Alias Types\n' - ' Documentation for objects representing parameterized ' - 'generic\n' - ' classes\n' - '\n' - ' Generics, user-defined generics and "typing.Generic"\n' - ' Documentation on how to implement generic classes that ' - 'can be\n' - ' parameterized at runtime and understood by static ' - 'type-checkers.\n' - '\n' - 'A class can *generally* only be parameterized if it defines ' - 'the\n' - 'special class method "__class_getitem__()".\n' - '\n' - 'classmethod object.__class_getitem__(cls, key)\n' - '\n' - ' Return an object representing the specialization of a ' - 'generic class\n' - ' by type arguments found in *key*.\n' - '\n' - ' When defined on a class, "__class_getitem__()" is ' - 'automatically a\n' - ' class method. As such, there is no need for it to be ' - 'decorated with\n' - ' "@classmethod" when it is defined.\n' - '\n' - '\n' - 'The purpose of *__class_getitem__*\n' - '----------------------------------\n' - '\n' - 'The purpose of "__class_getitem__()" is to allow runtime\n' - 'parameterization of standard-library generic classes in ' - 'order to more\n' - 'easily apply *type hints* to these classes.\n' - '\n' - 'To implement custom generic classes that can be ' - 'parameterized at\n' - 'runtime and understood by static type-checkers, users should ' - 'either\n' - 'inherit from a standard library class that already ' - 'implements\n' - '"__class_getitem__()", or inherit from "typing.Generic", ' - 'which has its\n' - 'own implementation of "__class_getitem__()".\n' - '\n' - 'Custom implementations of "__class_getitem__()" on classes ' - 'defined\n' - 'outside of the standard library may not be understood by ' - 'third-party\n' - 'type-checkers such as mypy. Using "__class_getitem__()" on ' - 'any class\n' - 'for purposes other than type hinting is discouraged.\n' - '\n' - '\n' - '*__class_getitem__* versus *__getitem__*\n' - '----------------------------------------\n' - '\n' - 'Usually, the subscription of an object using square brackets ' - 'will call\n' - 'the "__getitem__()" instance method defined on the object’s ' - 'class.\n' - 'However, if the object being subscribed is itself a class, ' - 'the class\n' - 'method "__class_getitem__()" may be called instead.\n' - '"__class_getitem__()" should return a GenericAlias object if ' - 'it is\n' - 'properly defined.\n' - '\n' - 'Presented with the *expression* "obj[x]", the Python ' - 'interpreter\n' - 'follows something like the following process to decide ' - 'whether\n' - '"__getitem__()" or "__class_getitem__()" should be called:\n' - '\n' - ' from inspect import isclass\n' - '\n' - ' def subscribe(obj, x):\n' - ' """Return the result of the expression `obj[x]`"""\n' - '\n' - ' class_of_obj = type(obj)\n' - '\n' - ' # If the class of obj defines __getitem__,\n' - ' # call class_of_obj.__getitem__(obj, x)\n' - " if hasattr(class_of_obj, '__getitem__'):\n" - ' return class_of_obj.__getitem__(obj, x)\n' - '\n' - ' # Else, if obj is a class and defines ' - '__class_getitem__,\n' - ' # call obj.__class_getitem__(x)\n' - ' elif isclass(obj) and hasattr(obj, ' - "'__class_getitem__'):\n" - ' return obj.__class_getitem__(x)\n' - '\n' - ' # Else, raise an exception\n' - ' else:\n' - ' raise TypeError(\n' - ' f"\'{class_of_obj.__name__}\' object is not ' - 'subscriptable"\n' - ' )\n' - '\n' - 'In Python, all classes are themselves instances of other ' - 'classes. The\n' - 'class of a class is known as that class’s *metaclass*, and ' - 'most\n' - 'classes have the "type" class as their metaclass. "type" ' - 'does not\n' - 'define "__getitem__()", meaning that expressions such as ' - '"list[int]",\n' - '"dict[str, float]" and "tuple[str, bytes]" all result in\n' - '"__class_getitem__()" being called:\n' - '\n' - ' >>> # list has class "type" as its metaclass, like most ' - 'classes:\n' - ' >>> type(list)\n' - " <class 'type'>\n" - ' >>> type(dict) == type(list) == type(tuple) == type(str) ' - '== type(bytes)\n' - ' True\n' - ' >>> # "list[int]" calls "list.__class_getitem__(int)"\n' - ' >>> list[int]\n' - ' list[int]\n' - ' >>> # list.__class_getitem__ returns a GenericAlias ' - 'object:\n' - ' >>> type(list[int])\n' - " <class 'types.GenericAlias'>\n" - '\n' - 'However, if a class has a custom metaclass that defines\n' - '"__getitem__()", subscribing the class may result in ' - 'different\n' - 'behaviour. An example of this can be found in the "enum" ' - 'module:\n' - '\n' - ' >>> from enum import Enum\n' - ' >>> class Menu(Enum):\n' - ' ... """A breakfast menu"""\n' - " ... SPAM = 'spam'\n" - " ... BACON = 'bacon'\n" - ' ...\n' - ' >>> # Enum classes have a custom metaclass:\n' - ' >>> type(Menu)\n' - " <class 'enum.EnumMeta'>\n" - ' >>> # EnumMeta defines __getitem__,\n' - ' >>> # so __class_getitem__ is not called,\n' - ' >>> # and the result is not a GenericAlias object:\n' - " >>> Menu['SPAM']\n" - " <Menu.SPAM: 'spam'>\n" - " >>> type(Menu['SPAM'])\n" - " <enum 'Menu'>\n" - '\n' - 'See also:\n' - '\n' - ' **PEP 560** - Core Support for typing module and generic ' - 'types\n' - ' Introducing "__class_getitem__()", and outlining when ' - 'a\n' - ' subscription results in "__class_getitem__()" being ' - 'called\n' - ' instead of "__getitem__()"\n' - '\n' - '\n' - 'Emulating callable objects\n' - '==========================\n' - '\n' - 'object.__call__(self[, args...])\n' - '\n' - ' Called when the instance is “called” as a function; if ' - 'this method\n' - ' is defined, "x(arg1, arg2, ...)" roughly translates to\n' - ' "type(x).__call__(x, arg1, ...)".\n' - '\n' - '\n' - 'Emulating container types\n' - '=========================\n' - '\n' - 'The following methods can be defined to implement container ' - 'objects.\n' - 'Containers usually are *sequences* (such as "lists" or ' - '"tuples") or\n' - '*mappings* (like "dictionaries"), but can represent other ' - 'containers\n' - 'as well. The first set of methods is used either to emulate ' - 'a\n' - 'sequence or to emulate a mapping; the difference is that for ' - 'a\n' - 'sequence, the allowable keys should be the integers *k* for ' - 'which "0\n' - '<= k < N" where *N* is the length of the sequence, or ' - '"slice" objects,\n' - 'which define a range of items. It is also recommended that ' - 'mappings\n' - 'provide the methods "keys()", "values()", "items()", ' - '"get()",\n' - '"clear()", "setdefault()", "pop()", "popitem()", "copy()", ' - 'and\n' - '"update()" behaving similar to those for Python’s standard\n' - '"dictionary" objects. The "collections.abc" module provides ' - 'a\n' - '"MutableMapping" *abstract base class* to help create those ' - 'methods\n' - 'from a base set of "__getitem__()", "__setitem__()", ' - '"__delitem__()",\n' - 'and "keys()". Mutable sequences should provide methods ' - '"append()",\n' - '"count()", "index()", "extend()", "insert()", "pop()", ' - '"remove()",\n' - '"reverse()" and "sort()", like Python standard "list" ' - 'objects.\n' - 'Finally, sequence types should implement addition (meaning\n' - 'concatenation) and multiplication (meaning repetition) by ' - 'defining the\n' - 'methods "__add__()", "__radd__()", "__iadd__()", ' - '"__mul__()",\n' - '"__rmul__()" and "__imul__()" described below; they should ' - 'not define\n' - 'other numerical operators. It is recommended that both ' - 'mappings and\n' - 'sequences implement the "__contains__()" method to allow ' - 'efficient use\n' - 'of the "in" operator; for mappings, "in" should search the ' - 'mapping’s\n' - 'keys; for sequences, it should search through the values. ' - 'It is\n' - 'further recommended that both mappings and sequences ' - 'implement the\n' - '"__iter__()" method to allow efficient iteration through ' - 'the\n' - 'container; for mappings, "__iter__()" should iterate through ' - 'the\n' - 'object’s keys; for sequences, it should iterate through the ' - 'values.\n' - '\n' - 'object.__len__(self)\n' - '\n' - ' Called to implement the built-in function "len()". ' - 'Should return\n' - ' the length of the object, an integer ">=" 0. Also, an ' - 'object that\n' - ' doesn’t define a "__bool__()" method and whose ' - '"__len__()" method\n' - ' returns zero is considered to be false in a Boolean ' - 'context.\n' - '\n' - ' **CPython implementation detail:** In CPython, the length ' - 'is\n' - ' required to be at most "sys.maxsize". If the length is ' - 'larger than\n' - ' "sys.maxsize" some features (such as "len()") may raise\n' - ' "OverflowError". To prevent raising "OverflowError" by ' - 'truth value\n' - ' testing, an object must define a "__bool__()" method.\n' - '\n' - 'object.__length_hint__(self)\n' - '\n' - ' Called to implement "operator.length_hint()". Should ' - 'return an\n' - ' estimated length for the object (which may be greater or ' - 'less than\n' - ' the actual length). The length must be an integer ">=" 0. ' - 'The\n' - ' return value may also be "NotImplemented", which is ' - 'treated the\n' - ' same as if the "__length_hint__" method didn’t exist at ' - 'all. This\n' - ' method is purely an optimization and is never required ' - 'for\n' - ' correctness.\n' - '\n' - ' New in version 3.4.\n' - '\n' - 'Note:\n' - '\n' - ' Slicing is done exclusively with the following three ' - 'methods. A\n' - ' call like\n' - '\n' - ' a[1:2] = b\n' - '\n' - ' is translated to\n' - '\n' - ' a[slice(1, 2, None)] = b\n' - '\n' - ' and so forth. Missing slice items are always filled in ' - 'with "None".\n' - '\n' - 'object.__getitem__(self, key)\n' - '\n' - ' Called to implement evaluation of "self[key]". For ' - '*sequence*\n' - ' types, the accepted keys should be integers and slice ' - 'objects.\n' - ' Note that the special interpretation of negative indexes ' - '(if the\n' - ' class wishes to emulate a *sequence* type) is up to the\n' - ' "__getitem__()" method. If *key* is of an inappropriate ' - 'type,\n' - ' "TypeError" may be raised; if of a value outside the set ' - 'of indexes\n' - ' for the sequence (after any special interpretation of ' - 'negative\n' - ' values), "IndexError" should be raised. For *mapping* ' - 'types, if\n' - ' *key* is missing (not in the container), "KeyError" ' - 'should be\n' - ' raised.\n' - '\n' - ' Note:\n' - '\n' - ' "for" loops expect that an "IndexError" will be raised ' - 'for\n' - ' illegal indexes to allow proper detection of the end of ' - 'the\n' - ' sequence.\n' - '\n' - ' Note:\n' - '\n' - ' When subscripting a *class*, the special class method\n' - ' "__class_getitem__()" may be called instead of ' - '"__getitem__()".\n' - ' See __class_getitem__ versus __getitem__ for more ' - 'details.\n' - '\n' - 'object.__setitem__(self, key, value)\n' - '\n' - ' Called to implement assignment to "self[key]". Same note ' - 'as for\n' - ' "__getitem__()". This should only be implemented for ' - 'mappings if\n' - ' the objects support changes to the values for keys, or if ' - 'new keys\n' - ' can be added, or for sequences if elements can be ' - 'replaced. The\n' - ' same exceptions should be raised for improper *key* ' - 'values as for\n' - ' the "__getitem__()" method.\n' - '\n' - 'object.__delitem__(self, key)\n' - '\n' - ' Called to implement deletion of "self[key]". Same note ' - 'as for\n' - ' "__getitem__()". This should only be implemented for ' - 'mappings if\n' - ' the objects support removal of keys, or for sequences if ' - 'elements\n' - ' can be removed from the sequence. The same exceptions ' - 'should be\n' - ' raised for improper *key* values as for the ' - '"__getitem__()" method.\n' - '\n' - 'object.__missing__(self, key)\n' - '\n' - ' Called by "dict"."__getitem__()" to implement "self[key]" ' - 'for dict\n' - ' subclasses when key is not in the dictionary.\n' - '\n' - 'object.__iter__(self)\n' - '\n' - ' This method is called when an *iterator* is required for ' - 'a\n' - ' container. This method should return a new iterator ' - 'object that can\n' - ' iterate over all the objects in the container. For ' - 'mappings, it\n' - ' should iterate over the keys of the container.\n' - '\n' - 'object.__reversed__(self)\n' - '\n' - ' Called (if present) by the "reversed()" built-in to ' - 'implement\n' - ' reverse iteration. It should return a new iterator ' - 'object that\n' - ' iterates over all the objects in the container in reverse ' - 'order.\n' - '\n' - ' If the "__reversed__()" method is not provided, the ' - '"reversed()"\n' - ' built-in will fall back to using the sequence protocol ' - '("__len__()"\n' - ' and "__getitem__()"). Objects that support the sequence ' - 'protocol\n' - ' should only provide "__reversed__()" if they can provide ' - 'an\n' - ' implementation that is more efficient than the one ' - 'provided by\n' - ' "reversed()".\n' - '\n' - 'The membership test operators ("in" and "not in") are ' - 'normally\n' - 'implemented as an iteration through a container. However, ' - 'container\n' - 'objects can supply the following special method with a more ' - 'efficient\n' - 'implementation, which also does not require the object be ' - 'iterable.\n' - '\n' - 'object.__contains__(self, item)\n' - '\n' - ' Called to implement membership test operators. Should ' - 'return true\n' - ' if *item* is in *self*, false otherwise. For mapping ' - 'objects, this\n' - ' should consider the keys of the mapping rather than the ' - 'values or\n' - ' the key-item pairs.\n' - '\n' - ' For objects that don’t define "__contains__()", the ' - 'membership test\n' - ' first tries iteration via "__iter__()", then the old ' - 'sequence\n' - ' iteration protocol via "__getitem__()", see this section ' - 'in the\n' - ' language reference.\n' - '\n' - '\n' - 'Emulating numeric types\n' - '=======================\n' - '\n' - 'The following methods can be defined to emulate numeric ' - 'objects.\n' - 'Methods corresponding to operations that are not supported ' - 'by the\n' - 'particular kind of number implemented (e.g., bitwise ' - 'operations for\n' - 'non-integral numbers) should be left undefined.\n' - '\n' - 'object.__add__(self, other)\n' - 'object.__sub__(self, other)\n' - 'object.__mul__(self, other)\n' - 'object.__matmul__(self, other)\n' - 'object.__truediv__(self, other)\n' - 'object.__floordiv__(self, other)\n' - 'object.__mod__(self, other)\n' - 'object.__divmod__(self, other)\n' - 'object.__pow__(self, other[, modulo])\n' - 'object.__lshift__(self, other)\n' - 'object.__rshift__(self, other)\n' - 'object.__and__(self, other)\n' - 'object.__xor__(self, other)\n' - 'object.__or__(self, other)\n' - '\n' - ' These methods are called to implement the binary ' - 'arithmetic\n' - ' operations ("+", "-", "*", "@", "/", "//", "%", ' - '"divmod()",\n' - ' "pow()", "**", "<<", ">>", "&", "^", "|"). For instance, ' - 'to\n' - ' evaluate the expression "x + y", where *x* is an instance ' - 'of a\n' - ' class that has an "__add__()" method, "x.__add__(y)" is ' - 'called.\n' - ' The "__divmod__()" method should be the equivalent to ' - 'using\n' - ' "__floordiv__()" and "__mod__()"; it should not be ' - 'related to\n' - ' "__truediv__()". Note that "__pow__()" should be defined ' - 'to accept\n' - ' an optional third argument if the ternary version of the ' - 'built-in\n' - ' "pow()" function is to be supported.\n' - '\n' - ' If one of those methods does not support the operation ' - 'with the\n' - ' supplied arguments, it should return "NotImplemented".\n' - '\n' - 'object.__radd__(self, other)\n' - 'object.__rsub__(self, other)\n' - 'object.__rmul__(self, other)\n' - 'object.__rmatmul__(self, other)\n' - 'object.__rtruediv__(self, other)\n' - 'object.__rfloordiv__(self, other)\n' - 'object.__rmod__(self, other)\n' - 'object.__rdivmod__(self, other)\n' - 'object.__rpow__(self, other[, modulo])\n' - 'object.__rlshift__(self, other)\n' - 'object.__rrshift__(self, other)\n' - 'object.__rand__(self, other)\n' - 'object.__rxor__(self, other)\n' - 'object.__ror__(self, other)\n' - '\n' - ' These methods are called to implement the binary ' - 'arithmetic\n' - ' operations ("+", "-", "*", "@", "/", "//", "%", ' - '"divmod()",\n' - ' "pow()", "**", "<<", ">>", "&", "^", "|") with reflected ' - '(swapped)\n' - ' operands. These functions are only called if the left ' - 'operand does\n' - ' not support the corresponding operation [3] and the ' - 'operands are of\n' - ' different types. [4] For instance, to evaluate the ' - 'expression "x -\n' - ' y", where *y* is an instance of a class that has an ' - '"__rsub__()"\n' - ' method, "y.__rsub__(x)" is called if "x.__sub__(y)" ' - 'returns\n' - ' *NotImplemented*.\n' - '\n' - ' Note that ternary "pow()" will not try calling ' - '"__rpow__()" (the\n' - ' coercion rules would become too complicated).\n' - '\n' - ' Note:\n' - '\n' - ' If the right operand’s type is a subclass of the left ' - 'operand’s\n' - ' type and that subclass provides a different ' - 'implementation of the\n' - ' reflected method for the operation, this method will be ' - 'called\n' - ' before the left operand’s non-reflected method. This ' - 'behavior\n' - ' allows subclasses to override their ancestors’ ' - 'operations.\n' - '\n' - 'object.__iadd__(self, other)\n' - 'object.__isub__(self, other)\n' - 'object.__imul__(self, other)\n' - 'object.__imatmul__(self, other)\n' - 'object.__itruediv__(self, other)\n' - 'object.__ifloordiv__(self, other)\n' - 'object.__imod__(self, other)\n' - 'object.__ipow__(self, other[, modulo])\n' - 'object.__ilshift__(self, other)\n' - 'object.__irshift__(self, other)\n' - 'object.__iand__(self, other)\n' - 'object.__ixor__(self, other)\n' - 'object.__ior__(self, other)\n' - '\n' - ' These methods are called to implement the augmented ' - 'arithmetic\n' - ' assignments ("+=", "-=", "*=", "@=", "/=", "//=", "%=", ' - '"**=",\n' - ' "<<=", ">>=", "&=", "^=", "|="). These methods should ' - 'attempt to\n' - ' do the operation in-place (modifying *self*) and return ' - 'the result\n' - ' (which could be, but does not have to be, *self*). If a ' - 'specific\n' - ' method is not defined, the augmented assignment falls ' - 'back to the\n' - ' normal methods. For instance, if *x* is an instance of a ' - 'class\n' - ' with an "__iadd__()" method, "x += y" is equivalent to "x ' - '=\n' - ' x.__iadd__(y)" . Otherwise, "x.__add__(y)" and ' - '"y.__radd__(x)" are\n' - ' considered, as with the evaluation of "x + y". In ' - 'certain\n' - ' situations, augmented assignment can result in unexpected ' - 'errors\n' - ' (see Why does a_tuple[i] += [‘item’] raise an exception ' - 'when the\n' - ' addition works?), but this behavior is in fact part of ' - 'the data\n' - ' model.\n' - '\n' - 'object.__neg__(self)\n' - 'object.__pos__(self)\n' - 'object.__abs__(self)\n' - 'object.__invert__(self)\n' - '\n' - ' Called to implement the unary arithmetic operations ("-", ' - '"+",\n' - ' "abs()" and "~").\n' - '\n' - 'object.__complex__(self)\n' - 'object.__int__(self)\n' - 'object.__float__(self)\n' - '\n' - ' Called to implement the built-in functions "complex()", ' - '"int()" and\n' - ' "float()". Should return a value of the appropriate ' - 'type.\n' - '\n' - 'object.__index__(self)\n' - '\n' - ' Called to implement "operator.index()", and whenever ' - 'Python needs\n' - ' to losslessly convert the numeric object to an integer ' - 'object (such\n' - ' as in slicing, or in the built-in "bin()", "hex()" and ' - '"oct()"\n' - ' functions). Presence of this method indicates that the ' - 'numeric\n' - ' object is an integer type. Must return an integer.\n' - '\n' - ' If "__int__()", "__float__()" and "__complex__()" are not ' - 'defined\n' - ' then corresponding built-in functions "int()", "float()" ' - 'and\n' - ' "complex()" fall back to "__index__()".\n' - '\n' - 'object.__round__(self[, ndigits])\n' - 'object.__trunc__(self)\n' - 'object.__floor__(self)\n' - 'object.__ceil__(self)\n' - '\n' - ' Called to implement the built-in function "round()" and ' - '"math"\n' - ' functions "trunc()", "floor()" and "ceil()". Unless ' - '*ndigits* is\n' - ' passed to "__round__()" all these methods should return ' - 'the value\n' - ' of the object truncated to an "Integral" (typically an ' - '"int").\n' - '\n' - ' The built-in function "int()" falls back to "__trunc__()" ' - 'if\n' - ' neither "__int__()" nor "__index__()" is defined.\n' - '\n' - '\n' - 'With Statement Context Managers\n' - '===============================\n' - '\n' - 'A *context manager* is an object that defines the runtime ' - 'context to\n' - 'be established when executing a "with" statement. The ' - 'context manager\n' - 'handles the entry into, and the exit from, the desired ' - 'runtime context\n' - 'for the execution of the block of code. Context managers ' - 'are normally\n' - 'invoked using the "with" statement (described in section The ' - 'with\n' - 'statement), but can also be used by directly invoking their ' - 'methods.\n' - '\n' - 'Typical uses of context managers include saving and ' - 'restoring various\n' - 'kinds of global state, locking and unlocking resources, ' - 'closing opened\n' - 'files, etc.\n' - '\n' - 'For more information on context managers, see Context ' - 'Manager Types.\n' - '\n' - 'object.__enter__(self)\n' - '\n' - ' Enter the runtime context related to this object. The ' - '"with"\n' - ' statement will bind this method’s return value to the ' - 'target(s)\n' - ' specified in the "as" clause of the statement, if any.\n' - '\n' - 'object.__exit__(self, exc_type, exc_value, traceback)\n' - '\n' - ' Exit the runtime context related to this object. The ' - 'parameters\n' - ' describe the exception that caused the context to be ' - 'exited. If the\n' - ' context was exited without an exception, all three ' - 'arguments will\n' - ' be "None".\n' - '\n' - ' If an exception is supplied, and the method wishes to ' - 'suppress the\n' - ' exception (i.e., prevent it from being propagated), it ' - 'should\n' - ' return a true value. Otherwise, the exception will be ' - 'processed\n' - ' normally upon exit from this method.\n' - '\n' - ' Note that "__exit__()" methods should not reraise the ' - 'passed-in\n' - ' exception; this is the caller’s responsibility.\n' - '\n' - 'See also:\n' - '\n' - ' **PEP 343** - The “with” statement\n' - ' The specification, background, and examples for the ' - 'Python "with"\n' - ' statement.\n' - '\n' - '\n' - 'Customizing positional arguments in class pattern matching\n' - '==========================================================\n' - '\n' - 'When using a class name in a pattern, positional arguments ' - 'in the\n' - 'pattern are not allowed by default, i.e. "case MyClass(x, ' - 'y)" is\n' - 'typically invalid without special support in "MyClass". To ' - 'be able to\n' - 'use that kind of patterns, the class needs to define a\n' - '*__match_args__* attribute.\n' - '\n' - 'object.__match_args__\n' - '\n' - ' This class variable can be assigned a tuple of strings. ' - 'When this\n' - ' class is used in a class pattern with positional ' - 'arguments, each\n' - ' positional argument will be converted into a keyword ' - 'argument,\n' - ' using the corresponding value in *__match_args__* as the ' - 'keyword.\n' - ' The absence of this attribute is equivalent to setting it ' - 'to "()".\n' - '\n' - 'For example, if "MyClass.__match_args__" is "("left", ' - '"center",\n' - '"right")" that means that "case MyClass(x, y)" is equivalent ' - 'to "case\n' - 'MyClass(left=x, center=y)". Note that the number of ' - 'arguments in the\n' - 'pattern must be smaller than or equal to the number of ' - 'elements in\n' - '*__match_args__*; if it is larger, the pattern match attempt ' - 'will\n' - 'raise a "TypeError".\n' - '\n' - 'New in version 3.10.\n' - '\n' - 'See also:\n' - '\n' - ' **PEP 634** - Structural Pattern Matching\n' - ' The specification for the Python "match" statement.\n' - '\n' - '\n' - 'Special method lookup\n' - '=====================\n' - '\n' - 'For custom classes, implicit invocations of special methods ' - 'are only\n' - 'guaranteed to work correctly if defined on an object’s type, ' - 'not in\n' - 'the object’s instance dictionary. That behaviour is the ' - 'reason why\n' - 'the following code raises an exception:\n' - '\n' - ' >>> class C:\n' - ' ... pass\n' - ' ...\n' - ' >>> c = C()\n' - ' >>> c.__len__ = lambda: 5\n' - ' >>> len(c)\n' - ' Traceback (most recent call last):\n' - ' File "<stdin>", line 1, in <module>\n' - " TypeError: object of type 'C' has no len()\n" - '\n' - 'The rationale behind this behaviour lies with a number of ' - 'special\n' - 'methods such as "__hash__()" and "__repr__()" that are ' - 'implemented by\n' - 'all objects, including type objects. If the implicit lookup ' - 'of these\n' - 'methods used the conventional lookup process, they would ' - 'fail when\n' - 'invoked on the type object itself:\n' - '\n' - ' >>> 1 .__hash__() == hash(1)\n' - ' True\n' - ' >>> int.__hash__() == hash(int)\n' - ' Traceback (most recent call last):\n' - ' File "<stdin>", line 1, in <module>\n' - " TypeError: descriptor '__hash__' of 'int' object needs an " - 'argument\n' - '\n' - 'Incorrectly attempting to invoke an unbound method of a ' - 'class in this\n' - 'way is sometimes referred to as ‘metaclass confusion’, and ' - 'is avoided\n' - 'by bypassing the instance when looking up special methods:\n' - '\n' - ' >>> type(1).__hash__(1) == hash(1)\n' - ' True\n' - ' >>> type(int).__hash__(int) == hash(int)\n' - ' True\n' - '\n' - 'In addition to bypassing any instance attributes in the ' - 'interest of\n' - 'correctness, implicit special method lookup generally also ' - 'bypasses\n' - 'the "__getattribute__()" method even of the object’s ' - 'metaclass:\n' - '\n' - ' >>> class Meta(type):\n' - ' ... def __getattribute__(*args):\n' - ' ... print("Metaclass getattribute invoked")\n' - ' ... return type.__getattribute__(*args)\n' - ' ...\n' - ' >>> class C(object, metaclass=Meta):\n' - ' ... def __len__(self):\n' - ' ... return 10\n' - ' ... def __getattribute__(*args):\n' - ' ... print("Class getattribute invoked")\n' - ' ... return object.__getattribute__(*args)\n' - ' ...\n' - ' >>> c = C()\n' - ' >>> c.__len__() # Explicit lookup via ' - 'instance\n' - ' Class getattribute invoked\n' - ' 10\n' - ' >>> type(c).__len__(c) # Explicit lookup via ' - 'type\n' - ' Metaclass getattribute invoked\n' - ' 10\n' - ' >>> len(c) # Implicit lookup\n' - ' 10\n' - '\n' - 'Bypassing the "__getattribute__()" machinery in this fashion ' - 'provides\n' - 'significant scope for speed optimisations within the ' - 'interpreter, at\n' - 'the cost of some flexibility in the handling of special ' - 'methods (the\n' - 'special method *must* be set on the class object itself in ' - 'order to be\n' - 'consistently invoked by the interpreter).\n', - 'string-methods': 'String Methods\n' - '**************\n' - '\n' - 'Strings implement all of the common sequence operations, ' - 'along with\n' - 'the additional methods described below.\n' - '\n' - 'Strings also support two styles of string formatting, one ' - 'providing a\n' - 'large degree of flexibility and customization (see ' - '"str.format()",\n' - 'Format String Syntax and Custom String Formatting) and the ' - 'other based\n' - 'on C "printf" style formatting that handles a narrower ' - 'range of types\n' - 'and is slightly harder to use correctly, but is often ' - 'faster for the\n' - 'cases it can handle (printf-style String Formatting).\n' - '\n' - 'The Text Processing Services section of the standard ' - 'library covers a\n' - 'number of other modules that provide various text related ' - 'utilities\n' - '(including regular expression support in the "re" ' - 'module).\n' - '\n' - 'str.capitalize()\n' - '\n' - ' Return a copy of the string with its first character ' - 'capitalized\n' - ' and the rest lowercased.\n' - '\n' - ' Changed in version 3.8: The first character is now put ' - 'into\n' - ' titlecase rather than uppercase. This means that ' - 'characters like\n' - ' digraphs will only have their first letter capitalized, ' - 'instead of\n' - ' the full character.\n' - '\n' - 'str.casefold()\n' - '\n' - ' Return a casefolded copy of the string. Casefolded ' - 'strings may be\n' - ' used for caseless matching.\n' - '\n' - ' Casefolding is similar to lowercasing but more ' - 'aggressive because\n' - ' it is intended to remove all case distinctions in a ' - 'string. For\n' - ' example, the German lowercase letter "\'ß\'" is ' - 'equivalent to ""ss"".\n' - ' Since it is already lowercase, "lower()" would do ' - 'nothing to "\'ß\'";\n' - ' "casefold()" converts it to ""ss"".\n' - '\n' - ' The casefolding algorithm is described in section 3.13 ' - 'of the\n' - ' Unicode Standard.\n' - '\n' - ' New in version 3.3.\n' - '\n' - 'str.center(width[, fillchar])\n' - '\n' - ' Return centered in a string of length *width*. Padding ' - 'is done\n' - ' using the specified *fillchar* (default is an ASCII ' - 'space). The\n' - ' original string is returned if *width* is less than or ' - 'equal to\n' - ' "len(s)".\n' - '\n' - 'str.count(sub[, start[, end]])\n' - '\n' - ' Return the number of non-overlapping occurrences of ' - 'substring *sub*\n' - ' in the range [*start*, *end*]. Optional arguments ' - '*start* and\n' - ' *end* are interpreted as in slice notation.\n' - '\n' - "str.encode(encoding='utf-8', errors='strict')\n" - '\n' - ' Return an encoded version of the string as a bytes ' - 'object. Default\n' - ' encoding is "\'utf-8\'". *errors* may be given to set a ' - 'different\n' - ' error handling scheme. The default for *errors* is ' - '"\'strict\'",\n' - ' meaning that encoding errors raise a "UnicodeError". ' - 'Other possible\n' - ' values are "\'ignore\'", "\'replace\'", ' - '"\'xmlcharrefreplace\'",\n' - ' "\'backslashreplace\'" and any other name registered ' - 'via\n' - ' "codecs.register_error()", see section Error Handlers. ' - 'For a list\n' - ' of possible encodings, see section Standard Encodings.\n' - '\n' - ' By default, the *errors* argument is not checked for ' - 'best\n' - ' performances, but only used at the first encoding ' - 'error. Enable the\n' - ' Python Development Mode, or use a debug build to check ' - '*errors*.\n' - '\n' - ' Changed in version 3.1: Support for keyword arguments ' - 'added.\n' - '\n' - ' Changed in version 3.9: The *errors* is now checked in ' - 'development\n' - ' mode and in debug mode.\n' - '\n' - 'str.endswith(suffix[, start[, end]])\n' - '\n' - ' Return "True" if the string ends with the specified ' - '*suffix*,\n' - ' otherwise return "False". *suffix* can also be a tuple ' - 'of suffixes\n' - ' to look for. With optional *start*, test beginning at ' - 'that\n' - ' position. With optional *end*, stop comparing at that ' - 'position.\n' - '\n' - 'str.expandtabs(tabsize=8)\n' - '\n' - ' Return a copy of the string where all tab characters ' - 'are replaced\n' - ' by one or more spaces, depending on the current column ' - 'and the\n' - ' given tab size. Tab positions occur every *tabsize* ' - 'characters\n' - ' (default is 8, giving tab positions at columns 0, 8, 16 ' - 'and so on).\n' - ' To expand the string, the current column is set to zero ' - 'and the\n' - ' string is examined character by character. If the ' - 'character is a\n' - ' tab ("\\t"), one or more space characters are inserted ' - 'in the result\n' - ' until the current column is equal to the next tab ' - 'position. (The\n' - ' tab character itself is not copied.) If the character ' - 'is a newline\n' - ' ("\\n") or return ("\\r"), it is copied and the current ' - 'column is\n' - ' reset to zero. Any other character is copied unchanged ' - 'and the\n' - ' current column is incremented by one regardless of how ' - 'the\n' - ' character is represented when printed.\n' - '\n' - " >>> '01\\t012\\t0123\\t01234'.expandtabs()\n" - " '01 012 0123 01234'\n" - " >>> '01\\t012\\t0123\\t01234'.expandtabs(4)\n" - " '01 012 0123 01234'\n" - '\n' - 'str.find(sub[, start[, end]])\n' - '\n' - ' Return the lowest index in the string where substring ' - '*sub* is\n' - ' found within the slice "s[start:end]". Optional ' - 'arguments *start*\n' - ' and *end* are interpreted as in slice notation. Return ' - '"-1" if\n' - ' *sub* is not found.\n' - '\n' - ' Note:\n' - '\n' - ' The "find()" method should be used only if you need ' - 'to know the\n' - ' position of *sub*. To check if *sub* is a substring ' - 'or not, use\n' - ' the "in" operator:\n' - '\n' - " >>> 'Py' in 'Python'\n" - ' True\n' - '\n' - 'str.format(*args, **kwargs)\n' - '\n' - ' Perform a string formatting operation. The string on ' - 'which this\n' - ' method is called can contain literal text or ' - 'replacement fields\n' - ' delimited by braces "{}". Each replacement field ' - 'contains either\n' - ' the numeric index of a positional argument, or the name ' - 'of a\n' - ' keyword argument. Returns a copy of the string where ' - 'each\n' - ' replacement field is replaced with the string value of ' - 'the\n' - ' corresponding argument.\n' - '\n' - ' >>> "The sum of 1 + 2 is {0}".format(1+2)\n' - " 'The sum of 1 + 2 is 3'\n" - '\n' - ' See Format String Syntax for a description of the ' - 'various\n' - ' formatting options that can be specified in format ' - 'strings.\n' - '\n' - ' Note:\n' - '\n' - ' When formatting a number ("int", "float", "complex",\n' - ' "decimal.Decimal" and subclasses) with the "n" type ' - '(ex:\n' - ' "\'{:n}\'.format(1234)"), the function temporarily ' - 'sets the\n' - ' "LC_CTYPE" locale to the "LC_NUMERIC" locale to ' - 'decode\n' - ' "decimal_point" and "thousands_sep" fields of ' - '"localeconv()" if\n' - ' they are non-ASCII or longer than 1 byte, and the ' - '"LC_NUMERIC"\n' - ' locale is different than the "LC_CTYPE" locale. This ' - 'temporary\n' - ' change affects other threads.\n' - '\n' - ' Changed in version 3.7: When formatting a number with ' - 'the "n" type,\n' - ' the function sets temporarily the "LC_CTYPE" locale to ' - 'the\n' - ' "LC_NUMERIC" locale in some cases.\n' - '\n' - 'str.format_map(mapping)\n' - '\n' - ' Similar to "str.format(**mapping)", except that ' - '"mapping" is used\n' - ' directly and not copied to a "dict". This is useful if ' - 'for example\n' - ' "mapping" is a dict subclass:\n' - '\n' - ' >>> class Default(dict):\n' - ' ... def __missing__(self, key):\n' - ' ... return key\n' - ' ...\n' - " >>> '{name} was born in " - "{country}'.format_map(Default(name='Guido'))\n" - " 'Guido was born in country'\n" - '\n' - ' New in version 3.2.\n' - '\n' - 'str.index(sub[, start[, end]])\n' - '\n' - ' Like "find()", but raise "ValueError" when the ' - 'substring is not\n' - ' found.\n' - '\n' - 'str.isalnum()\n' - '\n' - ' Return "True" if all characters in the string are ' - 'alphanumeric and\n' - ' there is at least one character, "False" otherwise. A ' - 'character\n' - ' "c" is alphanumeric if one of the following returns ' - '"True":\n' - ' "c.isalpha()", "c.isdecimal()", "c.isdigit()", or ' - '"c.isnumeric()".\n' - '\n' - 'str.isalpha()\n' - '\n' - ' Return "True" if all characters in the string are ' - 'alphabetic and\n' - ' there is at least one character, "False" otherwise. ' - 'Alphabetic\n' - ' characters are those characters defined in the Unicode ' - 'character\n' - ' database as “Letter”, i.e., those with general category ' - 'property\n' - ' being one of “Lm”, “Lt”, “Lu”, “Ll”, or “Lo”. Note ' - 'that this is\n' - ' different from the “Alphabetic” property defined in the ' - 'Unicode\n' - ' Standard.\n' - '\n' - 'str.isascii()\n' - '\n' - ' Return "True" if the string is empty or all characters ' - 'in the\n' - ' string are ASCII, "False" otherwise. ASCII characters ' - 'have code\n' - ' points in the range U+0000-U+007F.\n' - '\n' - ' New in version 3.7.\n' - '\n' - 'str.isdecimal()\n' - '\n' - ' Return "True" if all characters in the string are ' - 'decimal\n' - ' characters and there is at least one character, "False" ' - 'otherwise.\n' - ' Decimal characters are those that can be used to form ' - 'numbers in\n' - ' base 10, e.g. U+0660, ARABIC-INDIC DIGIT ZERO. ' - 'Formally a decimal\n' - ' character is a character in the Unicode General ' - 'Category “Nd”.\n' - '\n' - 'str.isdigit()\n' - '\n' - ' Return "True" if all characters in the string are ' - 'digits and there\n' - ' is at least one character, "False" otherwise. Digits ' - 'include\n' - ' decimal characters and digits that need special ' - 'handling, such as\n' - ' the compatibility superscript digits. This covers ' - 'digits which\n' - ' cannot be used to form numbers in base 10, like the ' - 'Kharosthi\n' - ' numbers. Formally, a digit is a character that has the ' - 'property\n' - ' value Numeric_Type=Digit or Numeric_Type=Decimal.\n' - '\n' - 'str.isidentifier()\n' - '\n' - ' Return "True" if the string is a valid identifier ' - 'according to the\n' - ' language definition, section Identifiers and keywords.\n' - '\n' - ' Call "keyword.iskeyword()" to test whether string "s" ' - 'is a reserved\n' - ' identifier, such as "def" and "class".\n' - '\n' - ' Example:\n' - '\n' - ' >>> from keyword import iskeyword\n' - '\n' - " >>> 'hello'.isidentifier(), iskeyword('hello')\n" - ' (True, False)\n' - " >>> 'def'.isidentifier(), iskeyword('def')\n" - ' (True, True)\n' - '\n' - 'str.islower()\n' - '\n' - ' Return "True" if all cased characters [4] in the string ' - 'are\n' - ' lowercase and there is at least one cased character, ' - '"False"\n' - ' otherwise.\n' - '\n' - 'str.isnumeric()\n' - '\n' - ' Return "True" if all characters in the string are ' - 'numeric\n' - ' characters, and there is at least one character, ' - '"False" otherwise.\n' - ' Numeric characters include digit characters, and all ' - 'characters\n' - ' that have the Unicode numeric value property, e.g. ' - 'U+2155, VULGAR\n' - ' FRACTION ONE FIFTH. Formally, numeric characters are ' - 'those with\n' - ' the property value Numeric_Type=Digit, ' - 'Numeric_Type=Decimal or\n' - ' Numeric_Type=Numeric.\n' - '\n' - 'str.isprintable()\n' - '\n' - ' Return "True" if all characters in the string are ' - 'printable or the\n' - ' string is empty, "False" otherwise. Nonprintable ' - 'characters are\n' - ' those characters defined in the Unicode character ' - 'database as\n' - ' “Other” or “Separator”, excepting the ASCII space ' - '(0x20) which is\n' - ' considered printable. (Note that printable characters ' - 'in this\n' - ' context are those which should not be escaped when ' - '"repr()" is\n' - ' invoked on a string. It has no bearing on the handling ' - 'of strings\n' - ' written to "sys.stdout" or "sys.stderr".)\n' - '\n' - 'str.isspace()\n' - '\n' - ' Return "True" if there are only whitespace characters ' - 'in the string\n' - ' and there is at least one character, "False" ' - 'otherwise.\n' - '\n' - ' A character is *whitespace* if in the Unicode character ' - 'database\n' - ' (see "unicodedata"), either its general category is ' - '"Zs"\n' - ' (“Separator, space”), or its bidirectional class is one ' - 'of "WS",\n' - ' "B", or "S".\n' - '\n' - 'str.istitle()\n' - '\n' - ' Return "True" if the string is a titlecased string and ' - 'there is at\n' - ' least one character, for example uppercase characters ' - 'may only\n' - ' follow uncased characters and lowercase characters only ' - 'cased ones.\n' - ' Return "False" otherwise.\n' - '\n' - 'str.isupper()\n' - '\n' - ' Return "True" if all cased characters [4] in the string ' - 'are\n' - ' uppercase and there is at least one cased character, ' - '"False"\n' - ' otherwise.\n' - '\n' - " >>> 'BANANA'.isupper()\n" - ' True\n' - " >>> 'banana'.isupper()\n" - ' False\n' - " >>> 'baNana'.isupper()\n" - ' False\n' - " >>> ' '.isupper()\n" - ' False\n' - '\n' - 'str.join(iterable)\n' - '\n' - ' Return a string which is the concatenation of the ' - 'strings in\n' - ' *iterable*. A "TypeError" will be raised if there are ' - 'any non-\n' - ' string values in *iterable*, including "bytes" ' - 'objects. The\n' - ' separator between elements is the string providing this ' - 'method.\n' - '\n' - 'str.ljust(width[, fillchar])\n' - '\n' - ' Return the string left justified in a string of length ' - '*width*.\n' - ' Padding is done using the specified *fillchar* (default ' - 'is an ASCII\n' - ' space). The original string is returned if *width* is ' - 'less than or\n' - ' equal to "len(s)".\n' - '\n' - 'str.lower()\n' - '\n' - ' Return a copy of the string with all the cased ' - 'characters [4]\n' - ' converted to lowercase.\n' - '\n' - ' The lowercasing algorithm used is described in section ' - '3.13 of the\n' - ' Unicode Standard.\n' - '\n' - 'str.lstrip([chars])\n' - '\n' - ' Return a copy of the string with leading characters ' - 'removed. The\n' - ' *chars* argument is a string specifying the set of ' - 'characters to be\n' - ' removed. If omitted or "None", the *chars* argument ' - 'defaults to\n' - ' removing whitespace. The *chars* argument is not a ' - 'prefix; rather,\n' - ' all combinations of its values are stripped:\n' - '\n' - " >>> ' spacious '.lstrip()\n" - " 'spacious '\n" - " >>> 'www.example.com'.lstrip('cmowz.')\n" - " 'example.com'\n" - '\n' - ' See "str.removeprefix()" for a method that will remove ' - 'a single\n' - ' prefix string rather than all of a set of characters. ' - 'For example:\n' - '\n' - " >>> 'Arthur: three!'.lstrip('Arthur: ')\n" - " 'ee!'\n" - " >>> 'Arthur: three!'.removeprefix('Arthur: ')\n" - " 'three!'\n" - '\n' - 'static str.maketrans(x[, y[, z]])\n' - '\n' - ' This static method returns a translation table usable ' - 'for\n' - ' "str.translate()".\n' - '\n' - ' If there is only one argument, it must be a dictionary ' - 'mapping\n' - ' Unicode ordinals (integers) or characters (strings of ' - 'length 1) to\n' - ' Unicode ordinals, strings (of arbitrary lengths) or ' - '"None".\n' - ' Character keys will then be converted to ordinals.\n' - '\n' - ' If there are two arguments, they must be strings of ' - 'equal length,\n' - ' and in the resulting dictionary, each character in x ' - 'will be mapped\n' - ' to the character at the same position in y. If there ' - 'is a third\n' - ' argument, it must be a string, whose characters will be ' - 'mapped to\n' - ' "None" in the result.\n' - '\n' - 'str.partition(sep)\n' - '\n' - ' Split the string at the first occurrence of *sep*, and ' - 'return a\n' - ' 3-tuple containing the part before the separator, the ' - 'separator\n' - ' itself, and the part after the separator. If the ' - 'separator is not\n' - ' found, return a 3-tuple containing the string itself, ' - 'followed by\n' - ' two empty strings.\n' - '\n' - 'str.removeprefix(prefix, /)\n' - '\n' - ' If the string starts with the *prefix* string, return\n' - ' "string[len(prefix):]". Otherwise, return a copy of the ' - 'original\n' - ' string:\n' - '\n' - " >>> 'TestHook'.removeprefix('Test')\n" - " 'Hook'\n" - " >>> 'BaseTestCase'.removeprefix('Test')\n" - " 'BaseTestCase'\n" - '\n' - ' New in version 3.9.\n' - '\n' - 'str.removesuffix(suffix, /)\n' - '\n' - ' If the string ends with the *suffix* string and that ' - '*suffix* is\n' - ' not empty, return "string[:-len(suffix)]". Otherwise, ' - 'return a copy\n' - ' of the original string:\n' - '\n' - " >>> 'MiscTests'.removesuffix('Tests')\n" - " 'Misc'\n" - " >>> 'TmpDirMixin'.removesuffix('Tests')\n" - " 'TmpDirMixin'\n" - '\n' - ' New in version 3.9.\n' - '\n' - 'str.replace(old, new[, count])\n' - '\n' - ' Return a copy of the string with all occurrences of ' - 'substring *old*\n' - ' replaced by *new*. If the optional argument *count* is ' - 'given, only\n' - ' the first *count* occurrences are replaced.\n' - '\n' - 'str.rfind(sub[, start[, end]])\n' - '\n' - ' Return the highest index in the string where substring ' - '*sub* is\n' - ' found, such that *sub* is contained within ' - '"s[start:end]".\n' - ' Optional arguments *start* and *end* are interpreted as ' - 'in slice\n' - ' notation. Return "-1" on failure.\n' - '\n' - 'str.rindex(sub[, start[, end]])\n' - '\n' - ' Like "rfind()" but raises "ValueError" when the ' - 'substring *sub* is\n' - ' not found.\n' - '\n' - 'str.rjust(width[, fillchar])\n' - '\n' - ' Return the string right justified in a string of length ' - '*width*.\n' - ' Padding is done using the specified *fillchar* (default ' - 'is an ASCII\n' - ' space). The original string is returned if *width* is ' - 'less than or\n' - ' equal to "len(s)".\n' - '\n' - 'str.rpartition(sep)\n' - '\n' - ' Split the string at the last occurrence of *sep*, and ' - 'return a\n' - ' 3-tuple containing the part before the separator, the ' - 'separator\n' - ' itself, and the part after the separator. If the ' - 'separator is not\n' - ' found, return a 3-tuple containing two empty strings, ' - 'followed by\n' - ' the string itself.\n' - '\n' - 'str.rsplit(sep=None, maxsplit=- 1)\n' - '\n' - ' Return a list of the words in the string, using *sep* ' - 'as the\n' - ' delimiter string. If *maxsplit* is given, at most ' - '*maxsplit* splits\n' - ' are done, the *rightmost* ones. If *sep* is not ' - 'specified or\n' - ' "None", any whitespace string is a separator. Except ' - 'for splitting\n' - ' from the right, "rsplit()" behaves like "split()" which ' - 'is\n' - ' described in detail below.\n' - '\n' - 'str.rstrip([chars])\n' - '\n' - ' Return a copy of the string with trailing characters ' - 'removed. The\n' - ' *chars* argument is a string specifying the set of ' - 'characters to be\n' - ' removed. If omitted or "None", the *chars* argument ' - 'defaults to\n' - ' removing whitespace. The *chars* argument is not a ' - 'suffix; rather,\n' - ' all combinations of its values are stripped:\n' - '\n' - " >>> ' spacious '.rstrip()\n" - " ' spacious'\n" - " >>> 'mississippi'.rstrip('ipz')\n" - " 'mississ'\n" - '\n' - ' See "str.removesuffix()" for a method that will remove ' - 'a single\n' - ' suffix string rather than all of a set of characters. ' - 'For example:\n' - '\n' - " >>> 'Monty Python'.rstrip(' Python')\n" - " 'M'\n" - " >>> 'Monty Python'.removesuffix(' Python')\n" - " 'Monty'\n" - '\n' - 'str.split(sep=None, maxsplit=- 1)\n' - '\n' - ' Return a list of the words in the string, using *sep* ' - 'as the\n' - ' delimiter string. If *maxsplit* is given, at most ' - '*maxsplit*\n' - ' splits are done (thus, the list will have at most ' - '"maxsplit+1"\n' - ' elements). If *maxsplit* is not specified or "-1", ' - 'then there is\n' - ' no limit on the number of splits (all possible splits ' - 'are made).\n' - '\n' - ' If *sep* is given, consecutive delimiters are not ' - 'grouped together\n' - ' and are deemed to delimit empty strings (for example,\n' - ' "\'1,,2\'.split(\',\')" returns "[\'1\', \'\', ' - '\'2\']"). The *sep* argument\n' - ' may consist of multiple characters (for example,\n' - ' "\'1<>2<>3\'.split(\'<>\')" returns "[\'1\', \'2\', ' - '\'3\']"). Splitting an\n' - ' empty string with a specified separator returns ' - '"[\'\']".\n' - '\n' - ' For example:\n' - '\n' - " >>> '1,2,3'.split(',')\n" - " ['1', '2', '3']\n" - " >>> '1,2,3'.split(',', maxsplit=1)\n" - " ['1', '2,3']\n" - " >>> '1,2,,3,'.split(',')\n" - " ['1', '2', '', '3', '']\n" - '\n' - ' If *sep* is not specified or is "None", a different ' - 'splitting\n' - ' algorithm is applied: runs of consecutive whitespace ' - 'are regarded\n' - ' as a single separator, and the result will contain no ' - 'empty strings\n' - ' at the start or end if the string has leading or ' - 'trailing\n' - ' whitespace. Consequently, splitting an empty string or ' - 'a string\n' - ' consisting of just whitespace with a "None" separator ' - 'returns "[]".\n' - '\n' - ' For example:\n' - '\n' - " >>> '1 2 3'.split()\n" - " ['1', '2', '3']\n" - " >>> '1 2 3'.split(maxsplit=1)\n" - " ['1', '2 3']\n" - " >>> ' 1 2 3 '.split()\n" - " ['1', '2', '3']\n" - '\n' - 'str.splitlines(keepends=False)\n' - '\n' - ' Return a list of the lines in the string, breaking at ' - 'line\n' - ' boundaries. Line breaks are not included in the ' - 'resulting list\n' - ' unless *keepends* is given and true.\n' - '\n' - ' This method splits on the following line boundaries. ' - 'In\n' - ' particular, the boundaries are a superset of *universal ' - 'newlines*.\n' - '\n' - ' ' - '+-------------------------+-------------------------------+\n' - ' | Representation | ' - 'Description |\n' - ' ' - '|=========================|===============================|\n' - ' | "\\n" | Line ' - 'Feed |\n' - ' ' - '+-------------------------+-------------------------------+\n' - ' | "\\r" | Carriage ' - 'Return |\n' - ' ' - '+-------------------------+-------------------------------+\n' - ' | "\\r\\n" | Carriage Return + Line ' - 'Feed |\n' - ' ' - '+-------------------------+-------------------------------+\n' - ' | "\\v" or "\\x0b" | Line ' - 'Tabulation |\n' - ' ' - '+-------------------------+-------------------------------+\n' - ' | "\\f" or "\\x0c" | Form ' - 'Feed |\n' - ' ' - '+-------------------------+-------------------------------+\n' - ' | "\\x1c" | File ' - 'Separator |\n' - ' ' - '+-------------------------+-------------------------------+\n' - ' | "\\x1d" | Group ' - 'Separator |\n' - ' ' - '+-------------------------+-------------------------------+\n' - ' | "\\x1e" | Record ' - 'Separator |\n' - ' ' - '+-------------------------+-------------------------------+\n' - ' | "\\x85" | Next Line (C1 Control ' - 'Code) |\n' - ' ' - '+-------------------------+-------------------------------+\n' - ' | "\\u2028" | Line ' - 'Separator |\n' - ' ' - '+-------------------------+-------------------------------+\n' - ' | "\\u2029" | Paragraph ' - 'Separator |\n' - ' ' - '+-------------------------+-------------------------------+\n' - '\n' - ' Changed in version 3.2: "\\v" and "\\f" added to list ' - 'of line\n' - ' boundaries.\n' - '\n' - ' For example:\n' - '\n' - " >>> 'ab c\\n\\nde fg\\rkl\\r\\n'.splitlines()\n" - " ['ab c', '', 'de fg', 'kl']\n" - " >>> 'ab c\\n\\nde " - "fg\\rkl\\r\\n'.splitlines(keepends=True)\n" - " ['ab c\\n', '\\n', 'de fg\\r', 'kl\\r\\n']\n" - '\n' - ' Unlike "split()" when a delimiter string *sep* is ' - 'given, this\n' - ' method returns an empty list for the empty string, and ' - 'a terminal\n' - ' line break does not result in an extra line:\n' - '\n' - ' >>> "".splitlines()\n' - ' []\n' - ' >>> "One line\\n".splitlines()\n' - " ['One line']\n" - '\n' - ' For comparison, "split(\'\\n\')" gives:\n' - '\n' - " >>> ''.split('\\n')\n" - " ['']\n" - " >>> 'Two lines\\n'.split('\\n')\n" - " ['Two lines', '']\n" - '\n' - 'str.startswith(prefix[, start[, end]])\n' - '\n' - ' Return "True" if string starts with the *prefix*, ' - 'otherwise return\n' - ' "False". *prefix* can also be a tuple of prefixes to ' - 'look for.\n' - ' With optional *start*, test string beginning at that ' - 'position.\n' - ' With optional *end*, stop comparing string at that ' - 'position.\n' - '\n' - 'str.strip([chars])\n' - '\n' - ' Return a copy of the string with the leading and ' - 'trailing\n' - ' characters removed. The *chars* argument is a string ' - 'specifying the\n' - ' set of characters to be removed. If omitted or "None", ' - 'the *chars*\n' - ' argument defaults to removing whitespace. The *chars* ' - 'argument is\n' - ' not a prefix or suffix; rather, all combinations of its ' - 'values are\n' - ' stripped:\n' - '\n' - " >>> ' spacious '.strip()\n" - " 'spacious'\n" - " >>> 'www.example.com'.strip('cmowz.')\n" - " 'example'\n" - '\n' - ' The outermost leading and trailing *chars* argument ' - 'values are\n' - ' stripped from the string. Characters are removed from ' - 'the leading\n' - ' end until reaching a string character that is not ' - 'contained in the\n' - ' set of characters in *chars*. A similar action takes ' - 'place on the\n' - ' trailing end. For example:\n' - '\n' - " >>> comment_string = '#....... Section 3.2.1 Issue " - "#32 .......'\n" - " >>> comment_string.strip('.#! ')\n" - " 'Section 3.2.1 Issue #32'\n" - '\n' - 'str.swapcase()\n' - '\n' - ' Return a copy of the string with uppercase characters ' - 'converted to\n' - ' lowercase and vice versa. Note that it is not ' - 'necessarily true that\n' - ' "s.swapcase().swapcase() == s".\n' - '\n' - 'str.title()\n' - '\n' - ' Return a titlecased version of the string where words ' - 'start with an\n' - ' uppercase character and the remaining characters are ' - 'lowercase.\n' - '\n' - ' For example:\n' - '\n' - " >>> 'Hello world'.title()\n" - " 'Hello World'\n" - '\n' - ' The algorithm uses a simple language-independent ' - 'definition of a\n' - ' word as groups of consecutive letters. The definition ' - 'works in\n' - ' many contexts but it means that apostrophes in ' - 'contractions and\n' - ' possessives form word boundaries, which may not be the ' - 'desired\n' - ' result:\n' - '\n' - ' >>> "they\'re bill\'s friends from the UK".title()\n' - ' "They\'Re Bill\'S Friends From The Uk"\n' - '\n' - ' The "string.capwords()" function does not have this ' - 'problem, as it\n' - ' splits words on spaces only.\n' - '\n' - ' Alternatively, a workaround for apostrophes can be ' - 'constructed\n' - ' using regular expressions:\n' - '\n' - ' >>> import re\n' - ' >>> def titlecase(s):\n' - ' ... return re.sub(r"[A-Za-z]+(\'[A-Za-z]+)?",\n' - ' ... lambda mo: ' - 'mo.group(0).capitalize(),\n' - ' ... s)\n' - ' ...\n' - ' >>> titlecase("they\'re bill\'s friends.")\n' - ' "They\'re Bill\'s Friends."\n' - '\n' - 'str.translate(table)\n' - '\n' - ' Return a copy of the string in which each character has ' - 'been mapped\n' - ' through the given translation table. The table must be ' - 'an object\n' - ' that implements indexing via "__getitem__()", typically ' - 'a *mapping*\n' - ' or *sequence*. When indexed by a Unicode ordinal (an ' - 'integer), the\n' - ' table object can do any of the following: return a ' - 'Unicode ordinal\n' - ' or a string, to map the character to one or more other ' - 'characters;\n' - ' return "None", to delete the character from the return ' - 'string; or\n' - ' raise a "LookupError" exception, to map the character ' - 'to itself.\n' - '\n' - ' You can use "str.maketrans()" to create a translation ' - 'map from\n' - ' character-to-character mappings in different formats.\n' - '\n' - ' See also the "codecs" module for a more flexible ' - 'approach to custom\n' - ' character mappings.\n' - '\n' - 'str.upper()\n' - '\n' - ' Return a copy of the string with all the cased ' - 'characters [4]\n' - ' converted to uppercase. Note that ' - '"s.upper().isupper()" might be\n' - ' "False" if "s" contains uncased characters or if the ' - 'Unicode\n' - ' category of the resulting character(s) is not “Lu” ' - '(Letter,\n' - ' uppercase), but e.g. “Lt” (Letter, titlecase).\n' - '\n' - ' The uppercasing algorithm used is described in section ' - '3.13 of the\n' - ' Unicode Standard.\n' - '\n' - 'str.zfill(width)\n' - '\n' - ' Return a copy of the string left filled with ASCII ' - '"\'0\'" digits to\n' - ' make a string of length *width*. A leading sign prefix\n' - ' ("\'+\'"/"\'-\'") is handled by inserting the padding ' - '*after* the sign\n' - ' character rather than before. The original string is ' - 'returned if\n' - ' *width* is less than or equal to "len(s)".\n' - '\n' - ' For example:\n' - '\n' - ' >>> "42".zfill(5)\n' - " '00042'\n" - ' >>> "-42".zfill(5)\n' - " '-0042'\n", - 'strings': 'String and Bytes literals\n' - '*************************\n' - '\n' - 'String literals are described by the following lexical ' - 'definitions:\n' - '\n' - ' stringliteral ::= [stringprefix](shortstring | longstring)\n' - ' stringprefix ::= "r" | "u" | "R" | "U" | "f" | "F"\n' - ' | "fr" | "Fr" | "fR" | "FR" | "rf" | "rF" | ' - '"Rf" | "RF"\n' - ' shortstring ::= "\'" shortstringitem* "\'" | \'"\' ' - 'shortstringitem* \'"\'\n' - ' longstring ::= "\'\'\'" longstringitem* "\'\'\'" | ' - '\'"""\' longstringitem* \'"""\'\n' - ' shortstringitem ::= shortstringchar | stringescapeseq\n' - ' longstringitem ::= longstringchar | stringescapeseq\n' - ' shortstringchar ::= <any source character except "\\" or ' - 'newline or the quote>\n' - ' longstringchar ::= <any source character except "\\">\n' - ' stringescapeseq ::= "\\" <any source character>\n' - '\n' - ' bytesliteral ::= bytesprefix(shortbytes | longbytes)\n' - ' bytesprefix ::= "b" | "B" | "br" | "Br" | "bR" | "BR" | ' - '"rb" | "rB" | "Rb" | "RB"\n' - ' shortbytes ::= "\'" shortbytesitem* "\'" | \'"\' ' - 'shortbytesitem* \'"\'\n' - ' longbytes ::= "\'\'\'" longbytesitem* "\'\'\'" | \'"""\' ' - 'longbytesitem* \'"""\'\n' - ' shortbytesitem ::= shortbyteschar | bytesescapeseq\n' - ' longbytesitem ::= longbyteschar | bytesescapeseq\n' - ' shortbyteschar ::= <any ASCII character except "\\" or newline ' - 'or the quote>\n' - ' longbyteschar ::= <any ASCII character except "\\">\n' - ' bytesescapeseq ::= "\\" <any ASCII character>\n' - '\n' - 'One syntactic restriction not indicated by these productions is ' - 'that\n' - 'whitespace is not allowed between the "stringprefix" or ' - '"bytesprefix"\n' - 'and the rest of the literal. The source character set is defined ' - 'by\n' - 'the encoding declaration; it is UTF-8 if no encoding declaration ' - 'is\n' - 'given in the source file; see section Encoding declarations.\n' - '\n' - 'In plain English: Both types of literals can be enclosed in ' - 'matching\n' - 'single quotes ("\'") or double quotes ("""). They can also be ' - 'enclosed\n' - 'in matching groups of three single or double quotes (these are\n' - 'generally referred to as *triple-quoted strings*). The backslash ' - '("\\")\n' - 'character is used to give special meaning to otherwise ordinary\n' - 'characters like "n", which means ‘newline’ when escaped ("\\n"). ' - 'It can\n' - 'also be used to escape characters that otherwise have a special\n' - 'meaning, such as newline, backslash itself, or the quote ' - 'character.\n' - 'See escape sequences below for examples.\n' - '\n' - 'Bytes literals are always prefixed with "\'b\'" or "\'B\'"; they ' - 'produce\n' - 'an instance of the "bytes" type instead of the "str" type. They ' - 'may\n' - 'only contain ASCII characters; bytes with a numeric value of 128 ' - 'or\n' - 'greater must be expressed with escapes.\n' - '\n' - 'Both string and bytes literals may optionally be prefixed with a\n' - 'letter "\'r\'" or "\'R\'"; such strings are called *raw strings* ' - 'and treat\n' - 'backslashes as literal characters. As a result, in string ' - 'literals,\n' - '"\'\\U\'" and "\'\\u\'" escapes in raw strings are not treated ' - 'specially.\n' - 'Given that Python 2.x’s raw unicode literals behave differently ' - 'than\n' - 'Python 3.x’s the "\'ur\'" syntax is not supported.\n' - '\n' - 'New in version 3.3: The "\'rb\'" prefix of raw bytes literals has ' - 'been\n' - 'added as a synonym of "\'br\'".\n' - '\n' - 'New in version 3.3: Support for the unicode legacy literal\n' - '("u\'value\'") was reintroduced to simplify the maintenance of ' - 'dual\n' - 'Python 2.x and 3.x codebases. See **PEP 414** for more ' - 'information.\n' - '\n' - 'A string literal with "\'f\'" or "\'F\'" in its prefix is a ' - '*formatted\n' - 'string literal*; see Formatted string literals. The "\'f\'" may ' - 'be\n' - 'combined with "\'r\'", but not with "\'b\'" or "\'u\'", therefore ' - 'raw\n' - 'formatted strings are possible, but formatted bytes literals are ' - 'not.\n' - '\n' - 'In triple-quoted literals, unescaped newlines and quotes are ' - 'allowed\n' - '(and are retained), except that three unescaped quotes in a row\n' - 'terminate the literal. (A “quote” is the character used to open ' - 'the\n' - 'literal, i.e. either "\'" or """.)\n' - '\n' - 'Unless an "\'r\'" or "\'R\'" prefix is present, escape sequences ' - 'in string\n' - 'and bytes literals are interpreted according to rules similar to ' - 'those\n' - 'used by Standard C. The recognized escape sequences are:\n' - '\n' - '+-------------------+-----------------------------------+---------+\n' - '| Escape Sequence | Meaning | Notes ' - '|\n' - '|===================|===================================|=========|\n' - '| "\\newline" | Backslash and newline ignored ' - '| |\n' - '+-------------------+-----------------------------------+---------+\n' - '| "\\\\" | Backslash ("\\") ' - '| |\n' - '+-------------------+-----------------------------------+---------+\n' - '| "\\\'" | Single quote ("\'") ' - '| |\n' - '+-------------------+-----------------------------------+---------+\n' - '| "\\"" | Double quote (""") ' - '| |\n' - '+-------------------+-----------------------------------+---------+\n' - '| "\\a" | ASCII Bell (BEL) ' - '| |\n' - '+-------------------+-----------------------------------+---------+\n' - '| "\\b" | ASCII Backspace (BS) ' - '| |\n' - '+-------------------+-----------------------------------+---------+\n' - '| "\\f" | ASCII Formfeed (FF) ' - '| |\n' - '+-------------------+-----------------------------------+---------+\n' - '| "\\n" | ASCII Linefeed (LF) ' - '| |\n' - '+-------------------+-----------------------------------+---------+\n' - '| "\\r" | ASCII Carriage Return (CR) ' - '| |\n' - '+-------------------+-----------------------------------+---------+\n' - '| "\\t" | ASCII Horizontal Tab (TAB) ' - '| |\n' - '+-------------------+-----------------------------------+---------+\n' - '| "\\v" | ASCII Vertical Tab (VT) ' - '| |\n' - '+-------------------+-----------------------------------+---------+\n' - '| "\\ooo" | Character with octal value *ooo* | ' - '(1,3) |\n' - '+-------------------+-----------------------------------+---------+\n' - '| "\\xhh" | Character with hex value *hh* | ' - '(2,3) |\n' - '+-------------------+-----------------------------------+---------+\n' - '\n' - 'Escape sequences only recognized in string literals are:\n' - '\n' - '+-------------------+-----------------------------------+---------+\n' - '| Escape Sequence | Meaning | Notes ' - '|\n' - '|===================|===================================|=========|\n' - '| "\\N{name}" | Character named *name* in the | ' - '(4) |\n' - '| | Unicode database | ' - '|\n' - '+-------------------+-----------------------------------+---------+\n' - '| "\\uxxxx" | Character with 16-bit hex value | ' - '(5) |\n' - '| | *xxxx* | ' - '|\n' - '+-------------------+-----------------------------------+---------+\n' - '| "\\Uxxxxxxxx" | Character with 32-bit hex value | ' - '(6) |\n' - '| | *xxxxxxxx* | ' - '|\n' - '+-------------------+-----------------------------------+---------+\n' - '\n' - 'Notes:\n' - '\n' - '1. As in Standard C, up to three octal digits are accepted.\n' - '\n' - '2. Unlike in Standard C, exactly two hex digits are required.\n' - '\n' - '3. In a bytes literal, hexadecimal and octal escapes denote the ' - 'byte\n' - ' with the given value. In a string literal, these escapes ' - 'denote a\n' - ' Unicode character with the given value.\n' - '\n' - '4. Changed in version 3.3: Support for name aliases [1] has been\n' - ' added.\n' - '\n' - '5. Exactly four hex digits are required.\n' - '\n' - '6. Any Unicode character can be encoded this way. Exactly eight ' - 'hex\n' - ' digits are required.\n' - '\n' - 'Unlike Standard C, all unrecognized escape sequences are left in ' - 'the\n' - 'string unchanged, i.e., *the backslash is left in the result*. ' - '(This\n' - 'behavior is useful when debugging: if an escape sequence is ' - 'mistyped,\n' - 'the resulting output is more easily recognized as broken.) It is ' - 'also\n' - 'important to note that the escape sequences only recognized in ' - 'string\n' - 'literals fall into the category of unrecognized escapes for ' - 'bytes\n' - 'literals.\n' - '\n' - ' Changed in version 3.6: Unrecognized escape sequences produce ' - 'a\n' - ' "DeprecationWarning". In a future Python version they will be ' - 'a\n' - ' "SyntaxWarning" and eventually a "SyntaxError".\n' - '\n' - 'Even in a raw literal, quotes can be escaped with a backslash, ' - 'but the\n' - 'backslash remains in the result; for example, "r"\\""" is a ' - 'valid\n' - 'string literal consisting of two characters: a backslash and a ' - 'double\n' - 'quote; "r"\\"" is not a valid string literal (even a raw string ' - 'cannot\n' - 'end in an odd number of backslashes). Specifically, *a raw ' - 'literal\n' - 'cannot end in a single backslash* (since the backslash would ' - 'escape\n' - 'the following quote character). Note also that a single ' - 'backslash\n' - 'followed by a newline is interpreted as those two characters as ' - 'part\n' - 'of the literal, *not* as a line continuation.\n', - 'subscriptions': 'Subscriptions\n' - '*************\n' - '\n' - 'The subscription of an instance of a container class will ' - 'generally\n' - 'select an element from the container. The subscription of a ' - '*generic\n' - 'class* will generally return a GenericAlias object.\n' - '\n' - ' subscription ::= primary "[" expression_list "]"\n' - '\n' - 'When an object is subscripted, the interpreter will ' - 'evaluate the\n' - 'primary and the expression list.\n' - '\n' - 'The primary must evaluate to an object that supports ' - 'subscription. An\n' - 'object may support subscription through defining one or ' - 'both of\n' - '"__getitem__()" and "__class_getitem__()". When the primary ' - 'is\n' - 'subscripted, the evaluated result of the expression list ' - 'will be\n' - 'passed to one of these methods. For more details on when\n' - '"__class_getitem__" is called instead of "__getitem__", ' - 'see\n' - '__class_getitem__ versus __getitem__.\n' - '\n' - 'If the expression list contains at least one comma, it will ' - 'evaluate\n' - 'to a "tuple" containing the items of the expression list. ' - 'Otherwise,\n' - 'the expression list will evaluate to the value of the ' - 'list’s sole\n' - 'member.\n' - '\n' - 'For built-in objects, there are two types of objects that ' - 'support\n' - 'subscription via "__getitem__()":\n' - '\n' - '1. Mappings. If the primary is a *mapping*, the expression ' - 'list must\n' - ' evaluate to an object whose value is one of the keys of ' - 'the\n' - ' mapping, and the subscription selects the value in the ' - 'mapping that\n' - ' corresponds to that key. An example of a builtin mapping ' - 'class is\n' - ' the "dict" class.\n' - '\n' - '2. Sequences. If the primary is a *sequence*, the ' - 'expression list must\n' - ' evaluate to an "int" or a "slice" (as discussed in the ' - 'following\n' - ' section). Examples of builtin sequence classes include ' - 'the "str",\n' - ' "list" and "tuple" classes.\n' - '\n' - 'The formal syntax makes no special provision for negative ' - 'indices in\n' - '*sequences*. However, built-in sequences all provide a ' - '"__getitem__()"\n' - 'method that interprets negative indices by adding the ' - 'length of the\n' - 'sequence to the index so that, for example, "x[-1]" selects ' - 'the last\n' - 'item of "x". The resulting value must be a nonnegative ' - 'integer less\n' - 'than the number of items in the sequence, and the ' - 'subscription selects\n' - 'the item whose index is that value (counting from zero). ' - 'Since the\n' - 'support for negative indices and slicing occurs in the ' - 'object’s\n' - '"__getitem__()" method, subclasses overriding this method ' - 'will need to\n' - 'explicitly add that support.\n' - '\n' - 'A "string" is a special kind of sequence whose items are ' - '*characters*.\n' - 'A character is not a separate data type but a string of ' - 'exactly one\n' - 'character.\n', - 'truth': 'Truth Value Testing\n' - '*******************\n' - '\n' - 'Any object can be tested for truth value, for use in an "if" or\n' - '"while" condition or as operand of the Boolean operations below.\n' - '\n' - 'By default, an object is considered true unless its class defines\n' - 'either a "__bool__()" method that returns "False" or a "__len__()"\n' - 'method that returns zero, when called with the object. [1] Here ' - 'are\n' - 'most of the built-in objects considered false:\n' - '\n' - '* constants defined to be false: "None" and "False".\n' - '\n' - '* zero of any numeric type: "0", "0.0", "0j", "Decimal(0)",\n' - ' "Fraction(0, 1)"\n' - '\n' - '* empty sequences and collections: "\'\'", "()", "[]", "{}", ' - '"set()",\n' - ' "range(0)"\n' - '\n' - 'Operations and built-in functions that have a Boolean result ' - 'always\n' - 'return "0" or "False" for false and "1" or "True" for true, unless\n' - 'otherwise stated. (Important exception: the Boolean operations ' - '"or"\n' - 'and "and" always return one of their operands.)\n', - 'try': 'The "try" statement\n' - '*******************\n' - '\n' - 'The "try" statement specifies exception handlers and/or cleanup code\n' - 'for a group of statements:\n' - '\n' - ' try_stmt ::= try1_stmt | try2_stmt\n' - ' try1_stmt ::= "try" ":" suite\n' - ' ("except" [expression ["as" identifier]] ":" ' - 'suite)+\n' - ' ["else" ":" suite]\n' - ' ["finally" ":" suite]\n' - ' try2_stmt ::= "try" ":" suite\n' - ' "finally" ":" suite\n' - '\n' - 'The "except" clause(s) specify one or more exception handlers. When ' - 'no\n' - 'exception occurs in the "try" clause, no exception handler is\n' - 'executed. When an exception occurs in the "try" suite, a search for ' - 'an\n' - 'exception handler is started. This search inspects the except ' - 'clauses\n' - 'in turn until one is found that matches the exception. An ' - 'expression-\n' - 'less except clause, if present, must be last; it matches any\n' - 'exception. For an except clause with an expression, that expression\n' - 'is evaluated, and the clause matches the exception if the resulting\n' - 'object is “compatible” with the exception. An object is compatible\n' - 'with an exception if the object is the class or a *non-virtual base\n' - 'class* of the exception object, or a tuple containing an item that ' - 'is\n' - 'the class or a non-virtual base class of the exception object.\n' - '\n' - 'If no except clause matches the exception, the search for an ' - 'exception\n' - 'handler continues in the surrounding code and on the invocation ' - 'stack.\n' - '[1]\n' - '\n' - 'If the evaluation of an expression in the header of an except clause\n' - 'raises an exception, the original search for a handler is canceled ' - 'and\n' - 'a search starts for the new exception in the surrounding code and on\n' - 'the call stack (it is treated as if the entire "try" statement ' - 'raised\n' - 'the exception).\n' - '\n' - 'When a matching except clause is found, the exception is assigned to\n' - 'the target specified after the "as" keyword in that except clause, ' - 'if\n' - 'present, and the except clause’s suite is executed. All except\n' - 'clauses must have an executable block. When the end of this block ' - 'is\n' - 'reached, execution continues normally after the entire try ' - 'statement.\n' - '(This means that if two nested handlers exist for the same ' - 'exception,\n' - 'and the exception occurs in the try clause of the inner handler, the\n' - 'outer handler will not handle the exception.)\n' - '\n' - 'When an exception has been assigned using "as target", it is cleared\n' - 'at the end of the except clause. This is as if\n' - '\n' - ' except E as N:\n' - ' foo\n' - '\n' - 'was translated to\n' - '\n' - ' except E as N:\n' - ' try:\n' - ' foo\n' - ' finally:\n' - ' del N\n' - '\n' - 'This means the exception must be assigned to a different name to be\n' - 'able to refer to it after the except clause. Exceptions are cleared\n' - 'because with the traceback attached to them, they form a reference\n' - 'cycle with the stack frame, keeping all locals in that frame alive\n' - 'until the next garbage collection occurs.\n' - '\n' - 'Before an except clause’s suite is executed, details about the\n' - 'exception are stored in the "sys" module and can be accessed via\n' - '"sys.exc_info()". "sys.exc_info()" returns a 3-tuple consisting of ' - 'the\n' - 'exception class, the exception instance and a traceback object (see\n' - 'section The standard type hierarchy) identifying the point in the\n' - 'program where the exception occurred. The details about the ' - 'exception\n' - 'accessed via "sys.exc_info()" are restored to their previous values\n' - 'when leaving an exception handler:\n' - '\n' - ' >>> print(sys.exc_info())\n' - ' (None, None, None)\n' - ' >>> try:\n' - ' ... raise TypeError\n' - ' ... except:\n' - ' ... print(sys.exc_info())\n' - ' ... try:\n' - ' ... raise ValueError\n' - ' ... except:\n' - ' ... print(sys.exc_info())\n' - ' ... print(sys.exc_info())\n' - ' ...\n' - " (<class 'TypeError'>, TypeError(), <traceback object at " - '0x10efad080>)\n' - " (<class 'ValueError'>, ValueError(), <traceback object at " - '0x10efad040>)\n' - " (<class 'TypeError'>, TypeError(), <traceback object at " - '0x10efad080>)\n' - ' >>> print(sys.exc_info())\n' - ' (None, None, None)\n' - '\n' - 'The optional "else" clause is executed if the control flow leaves ' - 'the\n' - '"try" suite, no exception was raised, and no "return", "continue", ' - 'or\n' - '"break" statement was executed. Exceptions in the "else" clause are\n' - 'not handled by the preceding "except" clauses.\n' - '\n' - 'If "finally" is present, it specifies a ‘cleanup’ handler. The ' - '"try"\n' - 'clause is executed, including any "except" and "else" clauses. If ' - 'an\n' - 'exception occurs in any of the clauses and is not handled, the\n' - 'exception is temporarily saved. The "finally" clause is executed. ' - 'If\n' - 'there is a saved exception it is re-raised at the end of the ' - '"finally"\n' - 'clause. If the "finally" clause raises another exception, the saved\n' - 'exception is set as the context of the new exception. If the ' - '"finally"\n' - 'clause executes a "return", "break" or "continue" statement, the ' - 'saved\n' - 'exception is discarded:\n' - '\n' - ' >>> def f():\n' - ' ... try:\n' - ' ... 1/0\n' - ' ... finally:\n' - ' ... return 42\n' - ' ...\n' - ' >>> f()\n' - ' 42\n' - '\n' - 'The exception information is not available to the program during\n' - 'execution of the "finally" clause.\n' - '\n' - 'When a "return", "break" or "continue" statement is executed in the\n' - '"try" suite of a "try"…"finally" statement, the "finally" clause is\n' - 'also executed ‘on the way out.’\n' - '\n' - 'The return value of a function is determined by the last "return"\n' - 'statement executed. Since the "finally" clause always executes, a\n' - '"return" statement executed in the "finally" clause will always be ' - 'the\n' - 'last one executed:\n' - '\n' - ' >>> def foo():\n' - ' ... try:\n' - " ... return 'try'\n" - ' ... finally:\n' - " ... return 'finally'\n" - ' ...\n' - ' >>> foo()\n' - " 'finally'\n" - '\n' - 'Additional information on exceptions can be found in section\n' - 'Exceptions, and information on using the "raise" statement to ' - 'generate\n' - 'exceptions may be found in section The raise statement.\n' - '\n' - 'Changed in version 3.8: Prior to Python 3.8, a "continue" statement\n' - 'was illegal in the "finally" clause due to a problem with the\n' - 'implementation.\n', - 'types': 'The standard type hierarchy\n' - '***************************\n' - '\n' - 'Below is a list of the types that are built into Python. ' - 'Extension\n' - 'modules (written in C, Java, or other languages, depending on the\n' - 'implementation) can define additional types. Future versions of\n' - 'Python may add types to the type hierarchy (e.g., rational ' - 'numbers,\n' - 'efficiently stored arrays of integers, etc.), although such ' - 'additions\n' - 'will often be provided via the standard library instead.\n' - '\n' - 'Some of the type descriptions below contain a paragraph listing\n' - '‘special attributes.’ These are attributes that provide access to ' - 'the\n' - 'implementation and are not intended for general use. Their ' - 'definition\n' - 'may change in the future.\n' - '\n' - 'None\n' - ' This type has a single value. There is a single object with ' - 'this\n' - ' value. This object is accessed through the built-in name "None". ' - 'It\n' - ' is used to signify the absence of a value in many situations, ' - 'e.g.,\n' - ' it is returned from functions that don’t explicitly return\n' - ' anything. Its truth value is false.\n' - '\n' - 'NotImplemented\n' - ' This type has a single value. There is a single object with ' - 'this\n' - ' value. This object is accessed through the built-in name\n' - ' "NotImplemented". Numeric methods and rich comparison methods\n' - ' should return this value if they do not implement the operation ' - 'for\n' - ' the operands provided. (The interpreter will then try the\n' - ' reflected operation, or some other fallback, depending on the\n' - ' operator.) It should not be evaluated in a boolean context.\n' - '\n' - ' See Implementing the arithmetic operations for more details.\n' - '\n' - ' Changed in version 3.9: Evaluating "NotImplemented" in a ' - 'boolean\n' - ' context is deprecated. While it currently evaluates as true, it\n' - ' will emit a "DeprecationWarning". It will raise a "TypeError" in ' - 'a\n' - ' future version of Python.\n' - '\n' - 'Ellipsis\n' - ' This type has a single value. There is a single object with ' - 'this\n' - ' value. This object is accessed through the literal "..." or the\n' - ' built-in name "Ellipsis". Its truth value is true.\n' - '\n' - '"numbers.Number"\n' - ' These are created by numeric literals and returned as results ' - 'by\n' - ' arithmetic operators and arithmetic built-in functions. ' - 'Numeric\n' - ' objects are immutable; once created their value never changes.\n' - ' Python numbers are of course strongly related to mathematical\n' - ' numbers, but subject to the limitations of numerical ' - 'representation\n' - ' in computers.\n' - '\n' - ' The string representations of the numeric classes, computed by\n' - ' "__repr__()" and "__str__()", have the following properties:\n' - '\n' - ' * They are valid numeric literals which, when passed to their ' - 'class\n' - ' constructor, produce an object having the value of the ' - 'original\n' - ' numeric.\n' - '\n' - ' * The representation is in base 10, when possible.\n' - '\n' - ' * Leading zeros, possibly excepting a single zero before a ' - 'decimal\n' - ' point, are not shown.\n' - '\n' - ' * Trailing zeros, possibly excepting a single zero after a ' - 'decimal\n' - ' point, are not shown.\n' - '\n' - ' * A sign is shown only when the number is negative.\n' - '\n' - ' Python distinguishes between integers, floating point numbers, ' - 'and\n' - ' complex numbers:\n' - '\n' - ' "numbers.Integral"\n' - ' These represent elements from the mathematical set of ' - 'integers\n' - ' (positive and negative).\n' - '\n' - ' There are two types of integers:\n' - '\n' - ' Integers ("int")\n' - ' These represent numbers in an unlimited range, subject to\n' - ' available (virtual) memory only. For the purpose of ' - 'shift\n' - ' and mask operations, a binary representation is assumed, ' - 'and\n' - ' negative numbers are represented in a variant of 2’s\n' - ' complement which gives the illusion of an infinite string ' - 'of\n' - ' sign bits extending to the left.\n' - '\n' - ' Booleans ("bool")\n' - ' These represent the truth values False and True. The two\n' - ' objects representing the values "False" and "True" are ' - 'the\n' - ' only Boolean objects. The Boolean type is a subtype of ' - 'the\n' - ' integer type, and Boolean values behave like the values 0 ' - 'and\n' - ' 1, respectively, in almost all contexts, the exception ' - 'being\n' - ' that when converted to a string, the strings ""False"" or\n' - ' ""True"" are returned, respectively.\n' - '\n' - ' The rules for integer representation are intended to give ' - 'the\n' - ' most meaningful interpretation of shift and mask operations\n' - ' involving negative integers.\n' - '\n' - ' "numbers.Real" ("float")\n' - ' These represent machine-level double precision floating ' - 'point\n' - ' numbers. You are at the mercy of the underlying machine\n' - ' architecture (and C or Java implementation) for the accepted\n' - ' range and handling of overflow. Python does not support ' - 'single-\n' - ' precision floating point numbers; the savings in processor ' - 'and\n' - ' memory usage that are usually the reason for using these are\n' - ' dwarfed by the overhead of using objects in Python, so there ' - 'is\n' - ' no reason to complicate the language with two kinds of ' - 'floating\n' - ' point numbers.\n' - '\n' - ' "numbers.Complex" ("complex")\n' - ' These represent complex numbers as a pair of machine-level\n' - ' double precision floating point numbers. The same caveats ' - 'apply\n' - ' as for floating point numbers. The real and imaginary parts ' - 'of a\n' - ' complex number "z" can be retrieved through the read-only\n' - ' attributes "z.real" and "z.imag".\n' - '\n' - 'Sequences\n' - ' These represent finite ordered sets indexed by non-negative\n' - ' numbers. The built-in function "len()" returns the number of ' - 'items\n' - ' of a sequence. When the length of a sequence is *n*, the index ' - 'set\n' - ' contains the numbers 0, 1, …, *n*-1. Item *i* of sequence *a* ' - 'is\n' - ' selected by "a[i]".\n' - '\n' - ' Sequences also support slicing: "a[i:j]" selects all items with\n' - ' index *k* such that *i* "<=" *k* "<" *j*. When used as an\n' - ' expression, a slice is a sequence of the same type. This ' - 'implies\n' - ' that the index set is renumbered so that it starts at 0.\n' - '\n' - ' Some sequences also support “extended slicing” with a third ' - '“step”\n' - ' parameter: "a[i:j:k]" selects all items of *a* with index *x* ' - 'where\n' - ' "x = i + n*k", *n* ">=" "0" and *i* "<=" *x* "<" *j*.\n' - '\n' - ' Sequences are distinguished according to their mutability:\n' - '\n' - ' Immutable sequences\n' - ' An object of an immutable sequence type cannot change once it ' - 'is\n' - ' created. (If the object contains references to other ' - 'objects,\n' - ' these other objects may be mutable and may be changed; ' - 'however,\n' - ' the collection of objects directly referenced by an ' - 'immutable\n' - ' object cannot change.)\n' - '\n' - ' The following types are immutable sequences:\n' - '\n' - ' Strings\n' - ' A string is a sequence of values that represent Unicode ' - 'code\n' - ' points. All the code points in the range "U+0000 - ' - 'U+10FFFF"\n' - ' can be represented in a string. Python doesn’t have a ' - '*char*\n' - ' type; instead, every code point in the string is ' - 'represented\n' - ' as a string object with length "1". The built-in ' - 'function\n' - ' "ord()" converts a code point from its string form to an\n' - ' integer in the range "0 - 10FFFF"; "chr()" converts an\n' - ' integer in the range "0 - 10FFFF" to the corresponding ' - 'length\n' - ' "1" string object. "str.encode()" can be used to convert ' - 'a\n' - ' "str" to "bytes" using the given text encoding, and\n' - ' "bytes.decode()" can be used to achieve the opposite.\n' - '\n' - ' Tuples\n' - ' The items of a tuple are arbitrary Python objects. Tuples ' - 'of\n' - ' two or more items are formed by comma-separated lists of\n' - ' expressions. A tuple of one item (a ‘singleton’) can be\n' - ' formed by affixing a comma to an expression (an expression ' - 'by\n' - ' itself does not create a tuple, since parentheses must be\n' - ' usable for grouping of expressions). An empty tuple can ' - 'be\n' - ' formed by an empty pair of parentheses.\n' - '\n' - ' Bytes\n' - ' A bytes object is an immutable array. The items are ' - '8-bit\n' - ' bytes, represented by integers in the range 0 <= x < 256.\n' - ' Bytes literals (like "b\'abc\'") and the built-in ' - '"bytes()"\n' - ' constructor can be used to create bytes objects. Also, ' - 'bytes\n' - ' objects can be decoded to strings via the "decode()" ' - 'method.\n' - '\n' - ' Mutable sequences\n' - ' Mutable sequences can be changed after they are created. ' - 'The\n' - ' subscription and slicing notations can be used as the target ' - 'of\n' - ' assignment and "del" (delete) statements.\n' - '\n' - ' There are currently two intrinsic mutable sequence types:\n' - '\n' - ' Lists\n' - ' The items of a list are arbitrary Python objects. Lists ' - 'are\n' - ' formed by placing a comma-separated list of expressions ' - 'in\n' - ' square brackets. (Note that there are no special cases ' - 'needed\n' - ' to form lists of length 0 or 1.)\n' - '\n' - ' Byte Arrays\n' - ' A bytearray object is a mutable array. They are created ' - 'by\n' - ' the built-in "bytearray()" constructor. Aside from being\n' - ' mutable (and hence unhashable), byte arrays otherwise ' - 'provide\n' - ' the same interface and functionality as immutable "bytes"\n' - ' objects.\n' - '\n' - ' The extension module "array" provides an additional example ' - 'of a\n' - ' mutable sequence type, as does the "collections" module.\n' - '\n' - 'Set types\n' - ' These represent unordered, finite sets of unique, immutable\n' - ' objects. As such, they cannot be indexed by any subscript. ' - 'However,\n' - ' they can be iterated over, and the built-in function "len()"\n' - ' returns the number of items in a set. Common uses for sets are ' - 'fast\n' - ' membership testing, removing duplicates from a sequence, and\n' - ' computing mathematical operations such as intersection, union,\n' - ' difference, and symmetric difference.\n' - '\n' - ' For set elements, the same immutability rules apply as for\n' - ' dictionary keys. Note that numeric types obey the normal rules ' - 'for\n' - ' numeric comparison: if two numbers compare equal (e.g., "1" and\n' - ' "1.0"), only one of them can be contained in a set.\n' - '\n' - ' There are currently two intrinsic set types:\n' - '\n' - ' Sets\n' - ' These represent a mutable set. They are created by the ' - 'built-in\n' - ' "set()" constructor and can be modified afterwards by ' - 'several\n' - ' methods, such as "add()".\n' - '\n' - ' Frozen sets\n' - ' These represent an immutable set. They are created by the\n' - ' built-in "frozenset()" constructor. As a frozenset is ' - 'immutable\n' - ' and *hashable*, it can be used again as an element of ' - 'another\n' - ' set, or as a dictionary key.\n' - '\n' - 'Mappings\n' - ' These represent finite sets of objects indexed by arbitrary ' - 'index\n' - ' sets. The subscript notation "a[k]" selects the item indexed by ' - '"k"\n' - ' from the mapping "a"; this can be used in expressions and as ' - 'the\n' - ' target of assignments or "del" statements. The built-in ' - 'function\n' - ' "len()" returns the number of items in a mapping.\n' - '\n' - ' There is currently a single intrinsic mapping type:\n' - '\n' - ' Dictionaries\n' - ' These represent finite sets of objects indexed by nearly\n' - ' arbitrary values. The only types of values not acceptable ' - 'as\n' - ' keys are values containing lists or dictionaries or other\n' - ' mutable types that are compared by value rather than by ' - 'object\n' - ' identity, the reason being that the efficient implementation ' - 'of\n' - ' dictionaries requires a key’s hash value to remain constant.\n' - ' Numeric types used for keys obey the normal rules for ' - 'numeric\n' - ' comparison: if two numbers compare equal (e.g., "1" and ' - '"1.0")\n' - ' then they can be used interchangeably to index the same\n' - ' dictionary entry.\n' - '\n' - ' Dictionaries preserve insertion order, meaning that keys will ' - 'be\n' - ' produced in the same order they were added sequentially over ' - 'the\n' - ' dictionary. Replacing an existing key does not change the ' - 'order,\n' - ' however removing a key and re-inserting it will add it to ' - 'the\n' - ' end instead of keeping its old place.\n' - '\n' - ' Dictionaries are mutable; they can be created by the "{...}"\n' - ' notation (see section Dictionary displays).\n' - '\n' - ' The extension modules "dbm.ndbm" and "dbm.gnu" provide\n' - ' additional examples of mapping types, as does the ' - '"collections"\n' - ' module.\n' - '\n' - ' Changed in version 3.7: Dictionaries did not preserve ' - 'insertion\n' - ' order in versions of Python before 3.6. In CPython 3.6,\n' - ' insertion order was preserved, but it was considered an\n' - ' implementation detail at that time rather than a language\n' - ' guarantee.\n' - '\n' - 'Callable types\n' - ' These are the types to which the function call operation (see\n' - ' section Calls) can be applied:\n' - '\n' - ' User-defined functions\n' - ' A user-defined function object is created by a function\n' - ' definition (see section Function definitions). It should be\n' - ' called with an argument list containing the same number of ' - 'items\n' - ' as the function’s formal parameter list.\n' - '\n' - ' Special attributes:\n' - '\n' - ' ' - '+---------------------------+---------------------------------+-------------+\n' - ' | Attribute | Meaning ' - '| |\n' - ' ' - '|===========================|=================================|=============|\n' - ' | "__doc__" | The function’s documentation ' - '| Writable |\n' - ' | | string, or "None" if ' - '| |\n' - ' | | unavailable; not inherited by ' - '| |\n' - ' | | subclasses. ' - '| |\n' - ' ' - '+---------------------------+---------------------------------+-------------+\n' - ' | "__name__" | The function’s name. ' - '| Writable |\n' - ' ' - '+---------------------------+---------------------------------+-------------+\n' - ' | "__qualname__" | The function’s *qualified ' - '| Writable |\n' - ' | | name*. New in version 3.3. ' - '| |\n' - ' ' - '+---------------------------+---------------------------------+-------------+\n' - ' | "__module__" | The name of the module the ' - '| Writable |\n' - ' | | function was defined in, or ' - '| |\n' - ' | | "None" if unavailable. ' - '| |\n' - ' ' - '+---------------------------+---------------------------------+-------------+\n' - ' | "__defaults__" | A tuple containing default ' - '| Writable |\n' - ' | | argument values for those ' - '| |\n' - ' | | arguments that have defaults, ' - '| |\n' - ' | | or "None" if no arguments have ' - '| |\n' - ' | | a default value. ' - '| |\n' - ' ' - '+---------------------------+---------------------------------+-------------+\n' - ' | "__code__" | The code object representing ' - '| Writable |\n' - ' | | the compiled function body. ' - '| |\n' - ' ' - '+---------------------------+---------------------------------+-------------+\n' - ' | "__globals__" | A reference to the dictionary ' - '| Read-only |\n' - ' | | that holds the function’s ' - '| |\n' - ' | | global variables — the global ' - '| |\n' - ' | | namespace of the module in ' - '| |\n' - ' | | which the function was defined. ' - '| |\n' - ' ' - '+---------------------------+---------------------------------+-------------+\n' - ' | "__dict__" | The namespace supporting ' - '| Writable |\n' - ' | | arbitrary function attributes. ' - '| |\n' - ' ' - '+---------------------------+---------------------------------+-------------+\n' - ' | "__closure__" | "None" or a tuple of cells that ' - '| Read-only |\n' - ' | | contain bindings for the ' - '| |\n' - ' | | function’s free variables. See ' - '| |\n' - ' | | below for information on the ' - '| |\n' - ' | | "cell_contents" attribute. ' - '| |\n' - ' ' - '+---------------------------+---------------------------------+-------------+\n' - ' | "__annotations__" | A dict containing annotations ' - '| Writable |\n' - ' | | of parameters. The keys of the ' - '| |\n' - ' | | dict are the parameter names, ' - '| |\n' - ' | | and "\'return\'" for the ' - 'return | |\n' - ' | | annotation, if provided. For ' - '| |\n' - ' | | more information on working ' - '| |\n' - ' | | with this attribute, see ' - '| |\n' - ' | | Annotations Best Practices. ' - '| |\n' - ' ' - '+---------------------------+---------------------------------+-------------+\n' - ' | "__kwdefaults__" | A dict containing defaults for ' - '| Writable |\n' - ' | | keyword-only parameters. ' - '| |\n' - ' ' - '+---------------------------+---------------------------------+-------------+\n' - '\n' - ' Most of the attributes labelled “Writable” check the type of ' - 'the\n' - ' assigned value.\n' - '\n' - ' Function objects also support getting and setting arbitrary\n' - ' attributes, which can be used, for example, to attach ' - 'metadata\n' - ' to functions. Regular attribute dot-notation is used to get ' - 'and\n' - ' set such attributes. *Note that the current implementation ' - 'only\n' - ' supports function attributes on user-defined functions. ' - 'Function\n' - ' attributes on built-in functions may be supported in the\n' - ' future.*\n' - '\n' - ' A cell object has the attribute "cell_contents". This can be\n' - ' used to get the value of the cell, as well as set the value.\n' - '\n' - ' Additional information about a function’s definition can be\n' - ' retrieved from its code object; see the description of ' - 'internal\n' - ' types below. The "cell" type can be accessed in the "types"\n' - ' module.\n' - '\n' - ' Instance methods\n' - ' An instance method object combines a class, a class instance ' - 'and\n' - ' any callable object (normally a user-defined function).\n' - '\n' - ' Special read-only attributes: "__self__" is the class ' - 'instance\n' - ' object, "__func__" is the function object; "__doc__" is the\n' - ' method’s documentation (same as "__func__.__doc__"); ' - '"__name__"\n' - ' is the method name (same as "__func__.__name__"); ' - '"__module__"\n' - ' is the name of the module the method was defined in, or ' - '"None"\n' - ' if unavailable.\n' - '\n' - ' Methods also support accessing (but not setting) the ' - 'arbitrary\n' - ' function attributes on the underlying function object.\n' - '\n' - ' User-defined method objects may be created when getting an\n' - ' attribute of a class (perhaps via an instance of that class), ' - 'if\n' - ' that attribute is a user-defined function object or a class\n' - ' method object.\n' - '\n' - ' When an instance method object is created by retrieving a ' - 'user-\n' - ' defined function object from a class via one of its ' - 'instances,\n' - ' its "__self__" attribute is the instance, and the method ' - 'object\n' - ' is said to be bound. The new method’s "__func__" attribute ' - 'is\n' - ' the original function object.\n' - '\n' - ' When an instance method object is created by retrieving a ' - 'class\n' - ' method object from a class or instance, its "__self__" ' - 'attribute\n' - ' is the class itself, and its "__func__" attribute is the\n' - ' function object underlying the class method.\n' - '\n' - ' When an instance method object is called, the underlying\n' - ' function ("__func__") is called, inserting the class ' - 'instance\n' - ' ("__self__") in front of the argument list. For instance, ' - 'when\n' - ' "C" is a class which contains a definition for a function ' - '"f()",\n' - ' and "x" is an instance of "C", calling "x.f(1)" is equivalent ' - 'to\n' - ' calling "C.f(x, 1)".\n' - '\n' - ' When an instance method object is derived from a class ' - 'method\n' - ' object, the “class instance” stored in "__self__" will ' - 'actually\n' - ' be the class itself, so that calling either "x.f(1)" or ' - '"C.f(1)"\n' - ' is equivalent to calling "f(C,1)" where "f" is the ' - 'underlying\n' - ' function.\n' - '\n' - ' Note that the transformation from function object to ' - 'instance\n' - ' method object happens each time the attribute is retrieved ' - 'from\n' - ' the instance. In some cases, a fruitful optimization is to\n' - ' assign the attribute to a local variable and call that local\n' - ' variable. Also notice that this transformation only happens ' - 'for\n' - ' user-defined functions; other callable objects (and all non-\n' - ' callable objects) are retrieved without transformation. It ' - 'is\n' - ' also important to note that user-defined functions which are\n' - ' attributes of a class instance are not converted to bound\n' - ' methods; this *only* happens when the function is an ' - 'attribute\n' - ' of the class.\n' - '\n' - ' Generator functions\n' - ' A function or method which uses the "yield" statement (see\n' - ' section The yield statement) is called a *generator ' - 'function*.\n' - ' Such a function, when called, always returns an *iterator*\n' - ' object which can be used to execute the body of the ' - 'function:\n' - ' calling the iterator’s "iterator.__next__()" method will ' - 'cause\n' - ' the function to execute until it provides a value using the\n' - ' "yield" statement. When the function executes a "return"\n' - ' statement or falls off the end, a "StopIteration" exception ' - 'is\n' - ' raised and the iterator will have reached the end of the set ' - 'of\n' - ' values to be returned.\n' - '\n' - ' Coroutine functions\n' - ' A function or method which is defined using "async def" is\n' - ' called a *coroutine function*. Such a function, when ' - 'called,\n' - ' returns a *coroutine* object. It may contain "await"\n' - ' expressions, as well as "async with" and "async for" ' - 'statements.\n' - ' See also the Coroutine Objects section.\n' - '\n' - ' Asynchronous generator functions\n' - ' A function or method which is defined using "async def" and\n' - ' which uses the "yield" statement is called a *asynchronous\n' - ' generator function*. Such a function, when called, returns ' - 'an\n' - ' *asynchronous iterator* object which can be used in an ' - '"async\n' - ' for" statement to execute the body of the function.\n' - '\n' - ' Calling the asynchronous iterator’s "aiterator.__anext__" ' - 'method\n' - ' will return an *awaitable* which when awaited will execute ' - 'until\n' - ' it provides a value using the "yield" expression. When the\n' - ' function executes an empty "return" statement or falls off ' - 'the\n' - ' end, a "StopAsyncIteration" exception is raised and the\n' - ' asynchronous iterator will have reached the end of the set ' - 'of\n' - ' values to be yielded.\n' - '\n' - ' Built-in functions\n' - ' A built-in function object is a wrapper around a C function.\n' - ' Examples of built-in functions are "len()" and "math.sin()"\n' - ' ("math" is a standard built-in module). The number and type ' - 'of\n' - ' the arguments are determined by the C function. Special ' - 'read-\n' - ' only attributes: "__doc__" is the function’s documentation\n' - ' string, or "None" if unavailable; "__name__" is the ' - 'function’s\n' - ' name; "__self__" is set to "None" (but see the next item);\n' - ' "__module__" is the name of the module the function was ' - 'defined\n' - ' in or "None" if unavailable.\n' - '\n' - ' Built-in methods\n' - ' This is really a different disguise of a built-in function, ' - 'this\n' - ' time containing an object passed to the C function as an\n' - ' implicit extra argument. An example of a built-in method is\n' - ' "alist.append()", assuming *alist* is a list object. In this\n' - ' case, the special read-only attribute "__self__" is set to ' - 'the\n' - ' object denoted by *alist*.\n' - '\n' - ' Classes\n' - ' Classes are callable. These objects normally act as ' - 'factories\n' - ' for new instances of themselves, but variations are possible ' - 'for\n' - ' class types that override "__new__()". The arguments of the\n' - ' call are passed to "__new__()" and, in the typical case, to\n' - ' "__init__()" to initialize the new instance.\n' - '\n' - ' Class Instances\n' - ' Instances of arbitrary classes can be made callable by ' - 'defining\n' - ' a "__call__()" method in their class.\n' - '\n' - 'Modules\n' - ' Modules are a basic organizational unit of Python code, and are\n' - ' created by the import system as invoked either by the "import"\n' - ' statement, or by calling functions such as\n' - ' "importlib.import_module()" and built-in "__import__()". A ' - 'module\n' - ' object has a namespace implemented by a dictionary object (this ' - 'is\n' - ' the dictionary referenced by the "__globals__" attribute of\n' - ' functions defined in the module). Attribute references are\n' - ' translated to lookups in this dictionary, e.g., "m.x" is ' - 'equivalent\n' - ' to "m.__dict__["x"]". A module object does not contain the code\n' - ' object used to initialize the module (since it isn’t needed ' - 'once\n' - ' the initialization is done).\n' - '\n' - ' Attribute assignment updates the module’s namespace dictionary,\n' - ' e.g., "m.x = 1" is equivalent to "m.__dict__["x"] = 1".\n' - '\n' - ' Predefined (writable) attributes:\n' - '\n' - ' "__name__"\n' - ' The module’s name.\n' - '\n' - ' "__doc__"\n' - ' The module’s documentation string, or "None" if ' - 'unavailable.\n' - '\n' - ' "__file__"\n' - ' The pathname of the file from which the module was loaded, ' - 'if\n' - ' it was loaded from a file. The "__file__" attribute may ' - 'be\n' - ' missing for certain types of modules, such as C modules ' - 'that\n' - ' are statically linked into the interpreter. For ' - 'extension\n' - ' modules loaded dynamically from a shared library, it’s ' - 'the\n' - ' pathname of the shared library file.\n' - '\n' - ' "__annotations__"\n' - ' A dictionary containing *variable annotations* collected\n' - ' during module body execution. For best practices on ' - 'working\n' - ' with "__annotations__", please see Annotations Best\n' - ' Practices.\n' - '\n' - ' Special read-only attribute: "__dict__" is the module’s ' - 'namespace\n' - ' as a dictionary object.\n' - '\n' - ' **CPython implementation detail:** Because of the way CPython\n' - ' clears module dictionaries, the module dictionary will be ' - 'cleared\n' - ' when the module falls out of scope even if the dictionary still ' - 'has\n' - ' live references. To avoid this, copy the dictionary or keep ' - 'the\n' - ' module around while using its dictionary directly.\n' - '\n' - 'Custom classes\n' - ' Custom class types are typically created by class definitions ' - '(see\n' - ' section Class definitions). A class has a namespace implemented ' - 'by\n' - ' a dictionary object. Class attribute references are translated ' - 'to\n' - ' lookups in this dictionary, e.g., "C.x" is translated to\n' - ' "C.__dict__["x"]" (although there are a number of hooks which ' - 'allow\n' - ' for other means of locating attributes). When the attribute name ' - 'is\n' - ' not found there, the attribute search continues in the base\n' - ' classes. This search of the base classes uses the C3 method\n' - ' resolution order which behaves correctly even in the presence ' - 'of\n' - ' ‘diamond’ inheritance structures where there are multiple\n' - ' inheritance paths leading back to a common ancestor. Additional\n' - ' details on the C3 MRO used by Python can be found in the\n' - ' documentation accompanying the 2.3 release at\n' - ' https://www.python.org/download/releases/2.3/mro/.\n' - '\n' - ' When a class attribute reference (for class "C", say) would ' - 'yield a\n' - ' class method object, it is transformed into an instance method\n' - ' object whose "__self__" attribute is "C". When it would yield ' - 'a\n' - ' static method object, it is transformed into the object wrapped ' - 'by\n' - ' the static method object. See section Implementing Descriptors ' - 'for\n' - ' another way in which attributes retrieved from a class may ' - 'differ\n' - ' from those actually contained in its "__dict__".\n' - '\n' - ' Class attribute assignments update the class’s dictionary, ' - 'never\n' - ' the dictionary of a base class.\n' - '\n' - ' A class object can be called (see above) to yield a class ' - 'instance\n' - ' (see below).\n' - '\n' - ' Special attributes:\n' - '\n' - ' "__name__"\n' - ' The class name.\n' - '\n' - ' "__module__"\n' - ' The name of the module in which the class was defined.\n' - '\n' - ' "__dict__"\n' - ' The dictionary containing the class’s namespace.\n' - '\n' - ' "__bases__"\n' - ' A tuple containing the base classes, in the order of ' - 'their\n' - ' occurrence in the base class list.\n' - '\n' - ' "__doc__"\n' - ' The class’s documentation string, or "None" if undefined.\n' - '\n' - ' "__annotations__"\n' - ' A dictionary containing *variable annotations* collected\n' - ' during class body execution. For best practices on ' - 'working\n' - ' with "__annotations__", please see Annotations Best\n' - ' Practices.\n' - '\n' - 'Class instances\n' - ' A class instance is created by calling a class object (see ' - 'above).\n' - ' A class instance has a namespace implemented as a dictionary ' - 'which\n' - ' is the first place in which attribute references are searched.\n' - ' When an attribute is not found there, and the instance’s class ' - 'has\n' - ' an attribute by that name, the search continues with the class\n' - ' attributes. If a class attribute is found that is a ' - 'user-defined\n' - ' function object, it is transformed into an instance method ' - 'object\n' - ' whose "__self__" attribute is the instance. Static method and\n' - ' class method objects are also transformed; see above under\n' - ' “Classes”. See section Implementing Descriptors for another way ' - 'in\n' - ' which attributes of a class retrieved via its instances may ' - 'differ\n' - ' from the objects actually stored in the class’s "__dict__". If ' - 'no\n' - ' class attribute is found, and the object’s class has a\n' - ' "__getattr__()" method, that is called to satisfy the lookup.\n' - '\n' - ' Attribute assignments and deletions update the instance’s\n' - ' dictionary, never a class’s dictionary. If the class has a\n' - ' "__setattr__()" or "__delattr__()" method, this is called ' - 'instead\n' - ' of updating the instance dictionary directly.\n' - '\n' - ' Class instances can pretend to be numbers, sequences, or ' - 'mappings\n' - ' if they have methods with certain special names. See section\n' - ' Special method names.\n' - '\n' - ' Special attributes: "__dict__" is the attribute dictionary;\n' - ' "__class__" is the instance’s class.\n' - '\n' - 'I/O objects (also known as file objects)\n' - ' A *file object* represents an open file. Various shortcuts are\n' - ' available to create file objects: the "open()" built-in ' - 'function,\n' - ' and also "os.popen()", "os.fdopen()", and the "makefile()" ' - 'method\n' - ' of socket objects (and perhaps by other functions or methods\n' - ' provided by extension modules).\n' - '\n' - ' The objects "sys.stdin", "sys.stdout" and "sys.stderr" are\n' - ' initialized to file objects corresponding to the interpreter’s\n' - ' standard input, output and error streams; they are all open in ' - 'text\n' - ' mode and therefore follow the interface defined by the\n' - ' "io.TextIOBase" abstract class.\n' - '\n' - 'Internal types\n' - ' A few types used internally by the interpreter are exposed to ' - 'the\n' - ' user. Their definitions may change with future versions of the\n' - ' interpreter, but they are mentioned here for completeness.\n' - '\n' - ' Code objects\n' - ' Code objects represent *byte-compiled* executable Python ' - 'code,\n' - ' or *bytecode*. The difference between a code object and a\n' - ' function object is that the function object contains an ' - 'explicit\n' - ' reference to the function’s globals (the module in which it ' - 'was\n' - ' defined), while a code object contains no context; also the\n' - ' default argument values are stored in the function object, ' - 'not\n' - ' in the code object (because they represent values calculated ' - 'at\n' - ' run-time). Unlike function objects, code objects are ' - 'immutable\n' - ' and contain no references (directly or indirectly) to ' - 'mutable\n' - ' objects.\n' - '\n' - ' Special read-only attributes: "co_name" gives the function ' - 'name;\n' - ' "co_argcount" is the total number of positional arguments\n' - ' (including positional-only arguments and arguments with ' - 'default\n' - ' values); "co_posonlyargcount" is the number of ' - 'positional-only\n' - ' arguments (including arguments with default values);\n' - ' "co_kwonlyargcount" is the number of keyword-only arguments\n' - ' (including arguments with default values); "co_nlocals" is ' - 'the\n' - ' number of local variables used by the function (including\n' - ' arguments); "co_varnames" is a tuple containing the names of ' - 'the\n' - ' local variables (starting with the argument names);\n' - ' "co_cellvars" is a tuple containing the names of local ' - 'variables\n' - ' that are referenced by nested functions; "co_freevars" is a\n' - ' tuple containing the names of free variables; "co_code" is a\n' - ' string representing the sequence of bytecode instructions;\n' - ' "co_consts" is a tuple containing the literals used by the\n' - ' bytecode; "co_names" is a tuple containing the names used by ' - 'the\n' - ' bytecode; "co_filename" is the filename from which the code ' - 'was\n' - ' compiled; "co_firstlineno" is the first line number of the\n' - ' function; "co_lnotab" is a string encoding the mapping from\n' - ' bytecode offsets to line numbers (for details see the source\n' - ' code of the interpreter); "co_stacksize" is the required ' - 'stack\n' - ' size; "co_flags" is an integer encoding a number of flags ' - 'for\n' - ' the interpreter.\n' - '\n' - ' The following flag bits are defined for "co_flags": bit ' - '"0x04"\n' - ' is set if the function uses the "*arguments" syntax to accept ' - 'an\n' - ' arbitrary number of positional arguments; bit "0x08" is set ' - 'if\n' - ' the function uses the "**keywords" syntax to accept ' - 'arbitrary\n' - ' keyword arguments; bit "0x20" is set if the function is a\n' - ' generator.\n' - '\n' - ' Future feature declarations ("from __future__ import ' - 'division")\n' - ' also use bits in "co_flags" to indicate whether a code ' - 'object\n' - ' was compiled with a particular feature enabled: bit "0x2000" ' - 'is\n' - ' set if the function was compiled with future division ' - 'enabled;\n' - ' bits "0x10" and "0x1000" were used in earlier versions of\n' - ' Python.\n' - '\n' - ' Other bits in "co_flags" are reserved for internal use.\n' - '\n' - ' If a code object represents a function, the first item in\n' - ' "co_consts" is the documentation string of the function, or\n' - ' "None" if undefined.\n' - '\n' - ' Frame objects\n' - ' Frame objects represent execution frames. They may occur in\n' - ' traceback objects (see below), and are also passed to ' - 'registered\n' - ' trace functions.\n' - '\n' - ' Special read-only attributes: "f_back" is to the previous ' - 'stack\n' - ' frame (towards the caller), or "None" if this is the bottom\n' - ' stack frame; "f_code" is the code object being executed in ' - 'this\n' - ' frame; "f_locals" is the dictionary used to look up local\n' - ' variables; "f_globals" is used for global variables;\n' - ' "f_builtins" is used for built-in (intrinsic) names; ' - '"f_lasti"\n' - ' gives the precise instruction (this is an index into the\n' - ' bytecode string of the code object).\n' - '\n' - ' Accessing "f_code" raises an auditing event ' - '"object.__getattr__"\n' - ' with arguments "obj" and ""f_code"".\n' - '\n' - ' Special writable attributes: "f_trace", if not "None", is a\n' - ' function called for various events during code execution ' - '(this\n' - ' is used by the debugger). Normally an event is triggered for\n' - ' each new source line - this can be disabled by setting\n' - ' "f_trace_lines" to "False".\n' - '\n' - ' Implementations *may* allow per-opcode events to be requested ' - 'by\n' - ' setting "f_trace_opcodes" to "True". Note that this may lead ' - 'to\n' - ' undefined interpreter behaviour if exceptions raised by the\n' - ' trace function escape to the function being traced.\n' - '\n' - ' "f_lineno" is the current line number of the frame — writing ' - 'to\n' - ' this from within a trace function jumps to the given line ' - '(only\n' - ' for the bottom-most frame). A debugger can implement a Jump\n' - ' command (aka Set Next Statement) by writing to f_lineno.\n' - '\n' - ' Frame objects support one method:\n' - '\n' - ' frame.clear()\n' - '\n' - ' This method clears all references to local variables held ' - 'by\n' - ' the frame. Also, if the frame belonged to a generator, ' - 'the\n' - ' generator is finalized. This helps break reference ' - 'cycles\n' - ' involving frame objects (for example when catching an\n' - ' exception and storing its traceback for later use).\n' - '\n' - ' "RuntimeError" is raised if the frame is currently ' - 'executing.\n' - '\n' - ' New in version 3.4.\n' - '\n' - ' Traceback objects\n' - ' Traceback objects represent a stack trace of an exception. ' - 'A\n' - ' traceback object is implicitly created when an exception ' - 'occurs,\n' - ' and may also be explicitly created by calling\n' - ' "types.TracebackType".\n' - '\n' - ' For implicitly created tracebacks, when the search for an\n' - ' exception handler unwinds the execution stack, at each ' - 'unwound\n' - ' level a traceback object is inserted in front of the current\n' - ' traceback. When an exception handler is entered, the stack\n' - ' trace is made available to the program. (See section The try\n' - ' statement.) It is accessible as the third item of the tuple\n' - ' returned by "sys.exc_info()", and as the "__traceback__"\n' - ' attribute of the caught exception.\n' - '\n' - ' When the program contains no suitable handler, the stack ' - 'trace\n' - ' is written (nicely formatted) to the standard error stream; ' - 'if\n' - ' the interpreter is interactive, it is also made available to ' - 'the\n' - ' user as "sys.last_traceback".\n' - '\n' - ' For explicitly created tracebacks, it is up to the creator ' - 'of\n' - ' the traceback to determine how the "tb_next" attributes ' - 'should\n' - ' be linked to form a full stack trace.\n' - '\n' - ' Special read-only attributes: "tb_frame" points to the ' - 'execution\n' - ' frame of the current level; "tb_lineno" gives the line ' - 'number\n' - ' where the exception occurred; "tb_lasti" indicates the ' - 'precise\n' - ' instruction. The line number and last instruction in the\n' - ' traceback may differ from the line number of its frame object ' - 'if\n' - ' the exception occurred in a "try" statement with no matching\n' - ' except clause or with a finally clause.\n' - '\n' - ' Accessing "tb_frame" raises an auditing event\n' - ' "object.__getattr__" with arguments "obj" and ""tb_frame"".\n' - '\n' - ' Special writable attribute: "tb_next" is the next level in ' - 'the\n' - ' stack trace (towards the frame where the exception occurred), ' - 'or\n' - ' "None" if there is no next level.\n' - '\n' - ' Changed in version 3.7: Traceback objects can now be ' - 'explicitly\n' - ' instantiated from Python code, and the "tb_next" attribute ' - 'of\n' - ' existing instances can be updated.\n' - '\n' - ' Slice objects\n' - ' Slice objects are used to represent slices for ' - '"__getitem__()"\n' - ' methods. They are also created by the built-in "slice()"\n' - ' function.\n' - '\n' - ' Special read-only attributes: "start" is the lower bound; ' - '"stop"\n' - ' is the upper bound; "step" is the step value; each is "None" ' - 'if\n' - ' omitted. These attributes can have any type.\n' - '\n' - ' Slice objects support one method:\n' - '\n' - ' slice.indices(self, length)\n' - '\n' - ' This method takes a single integer argument *length* and\n' - ' computes information about the slice that the slice ' - 'object\n' - ' would describe if applied to a sequence of *length* ' - 'items.\n' - ' It returns a tuple of three integers; respectively these ' - 'are\n' - ' the *start* and *stop* indices and the *step* or stride\n' - ' length of the slice. Missing or out-of-bounds indices are\n' - ' handled in a manner consistent with regular slices.\n' - '\n' - ' Static method objects\n' - ' Static method objects provide a way of defeating the\n' - ' transformation of function objects to method objects ' - 'described\n' - ' above. A static method object is a wrapper around any other\n' - ' object, usually a user-defined method object. When a static\n' - ' method object is retrieved from a class or a class instance, ' - 'the\n' - ' object actually returned is the wrapped object, which is not\n' - ' subject to any further transformation. Static method objects ' - 'are\n' - ' also callable. Static method objects are created by the ' - 'built-in\n' - ' "staticmethod()" constructor.\n' - '\n' - ' Class method objects\n' - ' A class method object, like a static method object, is a ' - 'wrapper\n' - ' around another object that alters the way in which that ' - 'object\n' - ' is retrieved from classes and class instances. The behaviour ' - 'of\n' - ' class method objects upon such retrieval is described above,\n' - ' under “User-defined methods”. Class method objects are ' - 'created\n' - ' by the built-in "classmethod()" constructor.\n', - 'typesfunctions': 'Functions\n' - '*********\n' - '\n' - 'Function objects are created by function definitions. The ' - 'only\n' - 'operation on a function object is to call it: ' - '"func(argument-list)".\n' - '\n' - 'There are really two flavors of function objects: built-in ' - 'functions\n' - 'and user-defined functions. Both support the same ' - 'operation (to call\n' - 'the function), but the implementation is different, hence ' - 'the\n' - 'different object types.\n' - '\n' - 'See Function definitions for more information.\n', - 'typesmapping': 'Mapping Types — "dict"\n' - '**********************\n' - '\n' - 'A *mapping* object maps *hashable* values to arbitrary ' - 'objects.\n' - 'Mappings are mutable objects. There is currently only one ' - 'standard\n' - 'mapping type, the *dictionary*. (For other containers see ' - 'the built-\n' - 'in "list", "set", and "tuple" classes, and the "collections" ' - 'module.)\n' - '\n' - 'A dictionary’s keys are *almost* arbitrary values. Values ' - 'that are\n' - 'not *hashable*, that is, values containing lists, ' - 'dictionaries or\n' - 'other mutable types (that are compared by value rather than ' - 'by object\n' - 'identity) may not be used as keys. Numeric types used for ' - 'keys obey\n' - 'the normal rules for numeric comparison: if two numbers ' - 'compare equal\n' - '(such as "1" and "1.0") then they can be used ' - 'interchangeably to index\n' - 'the same dictionary entry. (Note however, that since ' - 'computers store\n' - 'floating-point numbers as approximations it is usually ' - 'unwise to use\n' - 'them as dictionary keys.)\n' - '\n' - 'class dict(**kwargs)\n' - 'class dict(mapping, **kwargs)\n' - 'class dict(iterable, **kwargs)\n' - '\n' - ' Return a new dictionary initialized from an optional ' - 'positional\n' - ' argument and a possibly empty set of keyword arguments.\n' - '\n' - ' Dictionaries can be created by several means:\n' - '\n' - ' * Use a comma-separated list of "key: value" pairs within ' - 'braces:\n' - ' "{\'jack\': 4098, \'sjoerd\': 4127}" or "{4098: ' - "'jack', 4127:\n" - ' \'sjoerd\'}"\n' - '\n' - ' * Use a dict comprehension: "{}", "{x: x ** 2 for x in ' - 'range(10)}"\n' - '\n' - ' * Use the type constructor: "dict()", "dict([(\'foo\', ' - "100), ('bar',\n" - ' 200)])", "dict(foo=100, bar=200)"\n' - '\n' - ' If no positional argument is given, an empty dictionary ' - 'is created.\n' - ' If a positional argument is given and it is a mapping ' - 'object, a\n' - ' dictionary is created with the same key-value pairs as ' - 'the mapping\n' - ' object. Otherwise, the positional argument must be an ' - '*iterable*\n' - ' object. Each item in the iterable must itself be an ' - 'iterable with\n' - ' exactly two objects. The first object of each item ' - 'becomes a key\n' - ' in the new dictionary, and the second object the ' - 'corresponding\n' - ' value. If a key occurs more than once, the last value ' - 'for that key\n' - ' becomes the corresponding value in the new dictionary.\n' - '\n' - ' If keyword arguments are given, the keyword arguments and ' - 'their\n' - ' values are added to the dictionary created from the ' - 'positional\n' - ' argument. If a key being added is already present, the ' - 'value from\n' - ' the keyword argument replaces the value from the ' - 'positional\n' - ' argument.\n' - '\n' - ' To illustrate, the following examples all return a ' - 'dictionary equal\n' - ' to "{"one": 1, "two": 2, "three": 3}":\n' - '\n' - ' >>> a = dict(one=1, two=2, three=3)\n' - " >>> b = {'one': 1, 'two': 2, 'three': 3}\n" - " >>> c = dict(zip(['one', 'two', 'three'], [1, 2, 3]))\n" - " >>> d = dict([('two', 2), ('one', 1), ('three', 3)])\n" - " >>> e = dict({'three': 3, 'one': 1, 'two': 2})\n" - " >>> f = dict({'one': 1, 'three': 3}, two=2)\n" - ' >>> a == b == c == d == e == f\n' - ' True\n' - '\n' - ' Providing keyword arguments as in the first example only ' - 'works for\n' - ' keys that are valid Python identifiers. Otherwise, any ' - 'valid keys\n' - ' can be used.\n' - '\n' - ' These are the operations that dictionaries support (and ' - 'therefore,\n' - ' custom mapping types should support too):\n' - '\n' - ' list(d)\n' - '\n' - ' Return a list of all the keys used in the dictionary ' - '*d*.\n' - '\n' - ' len(d)\n' - '\n' - ' Return the number of items in the dictionary *d*.\n' - '\n' - ' d[key]\n' - '\n' - ' Return the item of *d* with key *key*. Raises a ' - '"KeyError" if\n' - ' *key* is not in the map.\n' - '\n' - ' If a subclass of dict defines a method "__missing__()" ' - 'and *key*\n' - ' is not present, the "d[key]" operation calls that ' - 'method with\n' - ' the key *key* as argument. The "d[key]" operation ' - 'then returns\n' - ' or raises whatever is returned or raised by the\n' - ' "__missing__(key)" call. No other operations or ' - 'methods invoke\n' - ' "__missing__()". If "__missing__()" is not defined, ' - '"KeyError"\n' - ' is raised. "__missing__()" must be a method; it cannot ' - 'be an\n' - ' instance variable:\n' - '\n' - ' >>> class Counter(dict):\n' - ' ... def __missing__(self, key):\n' - ' ... return 0\n' - ' >>> c = Counter()\n' - " >>> c['red']\n" - ' 0\n' - " >>> c['red'] += 1\n" - " >>> c['red']\n" - ' 1\n' - '\n' - ' The example above shows part of the implementation of\n' - ' "collections.Counter". A different "__missing__" ' - 'method is used\n' - ' by "collections.defaultdict".\n' - '\n' - ' d[key] = value\n' - '\n' - ' Set "d[key]" to *value*.\n' - '\n' - ' del d[key]\n' - '\n' - ' Remove "d[key]" from *d*. Raises a "KeyError" if ' - '*key* is not\n' - ' in the map.\n' - '\n' - ' key in d\n' - '\n' - ' Return "True" if *d* has a key *key*, else "False".\n' - '\n' - ' key not in d\n' - '\n' - ' Equivalent to "not key in d".\n' - '\n' - ' iter(d)\n' - '\n' - ' Return an iterator over the keys of the dictionary. ' - 'This is a\n' - ' shortcut for "iter(d.keys())".\n' - '\n' - ' clear()\n' - '\n' - ' Remove all items from the dictionary.\n' - '\n' - ' copy()\n' - '\n' - ' Return a shallow copy of the dictionary.\n' - '\n' - ' classmethod fromkeys(iterable[, value])\n' - '\n' - ' Create a new dictionary with keys from *iterable* and ' - 'values set\n' - ' to *value*.\n' - '\n' - ' "fromkeys()" is a class method that returns a new ' - 'dictionary.\n' - ' *value* defaults to "None". All of the values refer ' - 'to just a\n' - ' single instance, so it generally doesn’t make sense ' - 'for *value*\n' - ' to be a mutable object such as an empty list. To get ' - 'distinct\n' - ' values, use a dict comprehension instead.\n' - '\n' - ' get(key[, default])\n' - '\n' - ' Return the value for *key* if *key* is in the ' - 'dictionary, else\n' - ' *default*. If *default* is not given, it defaults to ' - '"None", so\n' - ' that this method never raises a "KeyError".\n' - '\n' - ' items()\n' - '\n' - ' Return a new view of the dictionary’s items ("(key, ' - 'value)"\n' - ' pairs). See the documentation of view objects.\n' - '\n' - ' keys()\n' - '\n' - ' Return a new view of the dictionary’s keys. See the\n' - ' documentation of view objects.\n' - '\n' - ' pop(key[, default])\n' - '\n' - ' If *key* is in the dictionary, remove it and return ' - 'its value,\n' - ' else return *default*. If *default* is not given and ' - '*key* is\n' - ' not in the dictionary, a "KeyError" is raised.\n' - '\n' - ' popitem()\n' - '\n' - ' Remove and return a "(key, value)" pair from the ' - 'dictionary.\n' - ' Pairs are returned in LIFO (last-in, first-out) ' - 'order.\n' - '\n' - ' "popitem()" is useful to destructively iterate over a\n' - ' dictionary, as often used in set algorithms. If the ' - 'dictionary\n' - ' is empty, calling "popitem()" raises a "KeyError".\n' - '\n' - ' Changed in version 3.7: LIFO order is now guaranteed. ' - 'In prior\n' - ' versions, "popitem()" would return an arbitrary ' - 'key/value pair.\n' - '\n' - ' reversed(d)\n' - '\n' - ' Return a reverse iterator over the keys of the ' - 'dictionary. This\n' - ' is a shortcut for "reversed(d.keys())".\n' - '\n' - ' New in version 3.8.\n' - '\n' - ' setdefault(key[, default])\n' - '\n' - ' If *key* is in the dictionary, return its value. If ' - 'not, insert\n' - ' *key* with a value of *default* and return *default*. ' - '*default*\n' - ' defaults to "None".\n' - '\n' - ' update([other])\n' - '\n' - ' Update the dictionary with the key/value pairs from ' - '*other*,\n' - ' overwriting existing keys. Return "None".\n' - '\n' - ' "update()" accepts either another dictionary object or ' - 'an\n' - ' iterable of key/value pairs (as tuples or other ' - 'iterables of\n' - ' length two). If keyword arguments are specified, the ' - 'dictionary\n' - ' is then updated with those key/value pairs: ' - '"d.update(red=1,\n' - ' blue=2)".\n' - '\n' - ' values()\n' - '\n' - ' Return a new view of the dictionary’s values. See ' - 'the\n' - ' documentation of view objects.\n' - '\n' - ' An equality comparison between one "dict.values()" ' - 'view and\n' - ' another will always return "False". This also applies ' - 'when\n' - ' comparing "dict.values()" to itself:\n' - '\n' - " >>> d = {'a': 1}\n" - ' >>> d.values() == d.values()\n' - ' False\n' - '\n' - ' d | other\n' - '\n' - ' Create a new dictionary with the merged keys and ' - 'values of *d*\n' - ' and *other*, which must both be dictionaries. The ' - 'values of\n' - ' *other* take priority when *d* and *other* share ' - 'keys.\n' - '\n' - ' New in version 3.9.\n' - '\n' - ' d |= other\n' - '\n' - ' Update the dictionary *d* with keys and values from ' - '*other*,\n' - ' which may be either a *mapping* or an *iterable* of ' - 'key/value\n' - ' pairs. The values of *other* take priority when *d* ' - 'and *other*\n' - ' share keys.\n' - '\n' - ' New in version 3.9.\n' - '\n' - ' Dictionaries compare equal if and only if they have the ' - 'same "(key,\n' - ' value)" pairs (regardless of ordering). Order comparisons ' - '(‘<’,\n' - ' ‘<=’, ‘>=’, ‘>’) raise "TypeError".\n' - '\n' - ' Dictionaries preserve insertion order. Note that ' - 'updating a key\n' - ' does not affect the order. Keys added after deletion are ' - 'inserted\n' - ' at the end.\n' - '\n' - ' >>> d = {"one": 1, "two": 2, "three": 3, "four": 4}\n' - ' >>> d\n' - " {'one': 1, 'two': 2, 'three': 3, 'four': 4}\n" - ' >>> list(d)\n' - " ['one', 'two', 'three', 'four']\n" - ' >>> list(d.values())\n' - ' [1, 2, 3, 4]\n' - ' >>> d["one"] = 42\n' - ' >>> d\n' - " {'one': 42, 'two': 2, 'three': 3, 'four': 4}\n" - ' >>> del d["two"]\n' - ' >>> d["two"] = None\n' - ' >>> d\n' - " {'one': 42, 'three': 3, 'four': 4, 'two': None}\n" - '\n' - ' Changed in version 3.7: Dictionary order is guaranteed to ' - 'be\n' - ' insertion order. This behavior was an implementation ' - 'detail of\n' - ' CPython from 3.6.\n' - '\n' - ' Dictionaries and dictionary views are reversible.\n' - '\n' - ' >>> d = {"one": 1, "two": 2, "three": 3, "four": 4}\n' - ' >>> d\n' - " {'one': 1, 'two': 2, 'three': 3, 'four': 4}\n" - ' >>> list(reversed(d))\n' - " ['four', 'three', 'two', 'one']\n" - ' >>> list(reversed(d.values()))\n' - ' [4, 3, 2, 1]\n' - ' >>> list(reversed(d.items()))\n' - " [('four', 4), ('three', 3), ('two', 2), ('one', 1)]\n" - '\n' - ' Changed in version 3.8: Dictionaries are now reversible.\n' - '\n' - 'See also:\n' - '\n' - ' "types.MappingProxyType" can be used to create a read-only ' - 'view of a\n' - ' "dict".\n' - '\n' - '\n' - 'Dictionary view objects\n' - '=======================\n' - '\n' - 'The objects returned by "dict.keys()", "dict.values()" and\n' - '"dict.items()" are *view objects*. They provide a dynamic ' - 'view on the\n' - 'dictionary’s entries, which means that when the dictionary ' - 'changes,\n' - 'the view reflects these changes.\n' - '\n' - 'Dictionary views can be iterated over to yield their ' - 'respective data,\n' - 'and support membership tests:\n' - '\n' - 'len(dictview)\n' - '\n' - ' Return the number of entries in the dictionary.\n' - '\n' - 'iter(dictview)\n' - '\n' - ' Return an iterator over the keys, values or items ' - '(represented as\n' - ' tuples of "(key, value)") in the dictionary.\n' - '\n' - ' Keys and values are iterated over in insertion order. ' - 'This allows\n' - ' the creation of "(value, key)" pairs using "zip()": ' - '"pairs =\n' - ' zip(d.values(), d.keys())". Another way to create the ' - 'same list is\n' - ' "pairs = [(v, k) for (k, v) in d.items()]".\n' - '\n' - ' Iterating views while adding or deleting entries in the ' - 'dictionary\n' - ' may raise a "RuntimeError" or fail to iterate over all ' - 'entries.\n' - '\n' - ' Changed in version 3.7: Dictionary order is guaranteed to ' - 'be\n' - ' insertion order.\n' - '\n' - 'x in dictview\n' - '\n' - ' Return "True" if *x* is in the underlying dictionary’s ' - 'keys, values\n' - ' or items (in the latter case, *x* should be a "(key, ' - 'value)"\n' - ' tuple).\n' - '\n' - 'reversed(dictview)\n' - '\n' - ' Return a reverse iterator over the keys, values or items ' - 'of the\n' - ' dictionary. The view will be iterated in reverse order of ' - 'the\n' - ' insertion.\n' - '\n' - ' Changed in version 3.8: Dictionary views are now ' - 'reversible.\n' - '\n' - 'dictview.mapping\n' - '\n' - ' Return a "types.MappingProxyType" that wraps the ' - 'original\n' - ' dictionary to which the view refers.\n' - '\n' - ' New in version 3.10.\n' - '\n' - 'Keys views are set-like since their entries are unique and ' - 'hashable.\n' - 'If all values are hashable, so that "(key, value)" pairs are ' - 'unique\n' - 'and hashable, then the items view is also set-like. (Values ' - 'views are\n' - 'not treated as set-like since the entries are generally not ' - 'unique.)\n' - 'For set-like views, all of the operations defined for the ' - 'abstract\n' - 'base class "collections.abc.Set" are available (for example, ' - '"==",\n' - '"<", or "^").\n' - '\n' - 'An example of dictionary view usage:\n' - '\n' - " >>> dishes = {'eggs': 2, 'sausage': 1, 'bacon': 1, " - "'spam': 500}\n" - ' >>> keys = dishes.keys()\n' - ' >>> values = dishes.values()\n' - '\n' - ' >>> # iteration\n' - ' >>> n = 0\n' - ' >>> for val in values:\n' - ' ... n += val\n' - ' >>> print(n)\n' - ' 504\n' - '\n' - ' >>> # keys and values are iterated over in the same order ' - '(insertion order)\n' - ' >>> list(keys)\n' - " ['eggs', 'sausage', 'bacon', 'spam']\n" - ' >>> list(values)\n' - ' [2, 1, 1, 500]\n' - '\n' - ' >>> # view objects are dynamic and reflect dict changes\n' - " >>> del dishes['eggs']\n" - " >>> del dishes['sausage']\n" - ' >>> list(keys)\n' - " ['bacon', 'spam']\n" - '\n' - ' >>> # set operations\n' - " >>> keys & {'eggs', 'bacon', 'salad'}\n" - " {'bacon'}\n" - " >>> keys ^ {'sausage', 'juice'}\n" - " {'juice', 'sausage', 'bacon', 'spam'}\n" - '\n' - ' >>> # get back a read-only proxy for the original ' - 'dictionary\n' - ' >>> values.mapping\n' - " mappingproxy({'eggs': 2, 'sausage': 1, 'bacon': 1, " - "'spam': 500})\n" - " >>> values.mapping['spam']\n" - ' 500\n', - 'typesmethods': 'Methods\n' - '*******\n' - '\n' - 'Methods are functions that are called using the attribute ' - 'notation.\n' - 'There are two flavors: built-in methods (such as "append()" ' - 'on lists)\n' - 'and class instance methods. Built-in methods are described ' - 'with the\n' - 'types that support them.\n' - '\n' - 'If you access a method (a function defined in a class ' - 'namespace)\n' - 'through an instance, you get a special object: a *bound ' - 'method* (also\n' - 'called *instance method*) object. When called, it will add ' - 'the "self"\n' - 'argument to the argument list. Bound methods have two ' - 'special read-\n' - 'only attributes: "m.__self__" is the object on which the ' - 'method\n' - 'operates, and "m.__func__" is the function implementing the ' - 'method.\n' - 'Calling "m(arg-1, arg-2, ..., arg-n)" is completely ' - 'equivalent to\n' - 'calling "m.__func__(m.__self__, arg-1, arg-2, ..., arg-n)".\n' - '\n' - 'Like function objects, bound method objects support getting ' - 'arbitrary\n' - 'attributes. However, since method attributes are actually ' - 'stored on\n' - 'the underlying function object ("meth.__func__"), setting ' - 'method\n' - 'attributes on bound methods is disallowed. Attempting to ' - 'set an\n' - 'attribute on a method results in an "AttributeError" being ' - 'raised. In\n' - 'order to set a method attribute, you need to explicitly set ' - 'it on the\n' - 'underlying function object:\n' - '\n' - ' >>> class C:\n' - ' ... def method(self):\n' - ' ... pass\n' - ' ...\n' - ' >>> c = C()\n' - " >>> c.method.whoami = 'my name is method' # can't set on " - 'the method\n' - ' Traceback (most recent call last):\n' - ' File "<stdin>", line 1, in <module>\n' - " AttributeError: 'method' object has no attribute " - "'whoami'\n" - " >>> c.method.__func__.whoami = 'my name is method'\n" - ' >>> c.method.whoami\n' - " 'my name is method'\n" - '\n' - 'See The standard type hierarchy for more information.\n', - 'typesmodules': 'Modules\n' - '*******\n' - '\n' - 'The only special operation on a module is attribute access: ' - '"m.name",\n' - 'where *m* is a module and *name* accesses a name defined in ' - '*m*’s\n' - 'symbol table. Module attributes can be assigned to. (Note ' - 'that the\n' - '"import" statement is not, strictly speaking, an operation ' - 'on a module\n' - 'object; "import foo" does not require a module object named ' - '*foo* to\n' - 'exist, rather it requires an (external) *definition* for a ' - 'module\n' - 'named *foo* somewhere.)\n' - '\n' - 'A special attribute of every module is "__dict__". This is ' - 'the\n' - 'dictionary containing the module’s symbol table. Modifying ' - 'this\n' - 'dictionary will actually change the module’s symbol table, ' - 'but direct\n' - 'assignment to the "__dict__" attribute is not possible (you ' - 'can write\n' - '"m.__dict__[\'a\'] = 1", which defines "m.a" to be "1", but ' - 'you can’t\n' - 'write "m.__dict__ = {}"). Modifying "__dict__" directly is ' - 'not\n' - 'recommended.\n' - '\n' - 'Modules built into the interpreter are written like this: ' - '"<module\n' - '\'sys\' (built-in)>". If loaded from a file, they are ' - 'written as\n' - '"<module \'os\' from ' - '\'/usr/local/lib/pythonX.Y/os.pyc\'>".\n', - 'typesseq': 'Sequence Types — "list", "tuple", "range"\n' - '*****************************************\n' - '\n' - 'There are three basic sequence types: lists, tuples, and range\n' - 'objects. Additional sequence types tailored for processing of ' - 'binary\n' - 'data and text strings are described in dedicated sections.\n' - '\n' - '\n' - 'Common Sequence Operations\n' - '==========================\n' - '\n' - 'The operations in the following table are supported by most ' - 'sequence\n' - 'types, both mutable and immutable. The ' - '"collections.abc.Sequence" ABC\n' - 'is provided to make it easier to correctly implement these ' - 'operations\n' - 'on custom sequence types.\n' - '\n' - 'This table lists the sequence operations sorted in ascending ' - 'priority.\n' - 'In the table, *s* and *t* are sequences of the same type, *n*, ' - '*i*,\n' - '*j* and *k* are integers and *x* is an arbitrary object that ' - 'meets any\n' - 'type and value restrictions imposed by *s*.\n' - '\n' - 'The "in" and "not in" operations have the same priorities as ' - 'the\n' - 'comparison operations. The "+" (concatenation) and "*" ' - '(repetition)\n' - 'operations have the same priority as the corresponding numeric\n' - 'operations. [3]\n' - '\n' - '+----------------------------+----------------------------------+------------+\n' - '| Operation | Result ' - '| Notes |\n' - '|============================|==================================|============|\n' - '| "x in s" | "True" if an item of *s* is ' - '| (1) |\n' - '| | equal to *x*, else "False" ' - '| |\n' - '+----------------------------+----------------------------------+------------+\n' - '| "x not in s" | "False" if an item of *s* is ' - '| (1) |\n' - '| | equal to *x*, else "True" ' - '| |\n' - '+----------------------------+----------------------------------+------------+\n' - '| "s + t" | the concatenation of *s* and *t* ' - '| (6)(7) |\n' - '+----------------------------+----------------------------------+------------+\n' - '| "s * n" or "n * s" | equivalent to adding *s* to ' - '| (2)(7) |\n' - '| | itself *n* times ' - '| |\n' - '+----------------------------+----------------------------------+------------+\n' - '| "s[i]" | *i*th item of *s*, origin 0 ' - '| (3) |\n' - '+----------------------------+----------------------------------+------------+\n' - '| "s[i:j]" | slice of *s* from *i* to *j* ' - '| (3)(4) |\n' - '+----------------------------+----------------------------------+------------+\n' - '| "s[i:j:k]" | slice of *s* from *i* to *j* ' - '| (3)(5) |\n' - '| | with step *k* ' - '| |\n' - '+----------------------------+----------------------------------+------------+\n' - '| "len(s)" | length of *s* ' - '| |\n' - '+----------------------------+----------------------------------+------------+\n' - '| "min(s)" | smallest item of *s* ' - '| |\n' - '+----------------------------+----------------------------------+------------+\n' - '| "max(s)" | largest item of *s* ' - '| |\n' - '+----------------------------+----------------------------------+------------+\n' - '| "s.index(x[, i[, j]])" | index of the first occurrence of ' - '| (8) |\n' - '| | *x* in *s* (at or after index ' - '| |\n' - '| | *i* and before index *j*) ' - '| |\n' - '+----------------------------+----------------------------------+------------+\n' - '| "s.count(x)" | total number of occurrences of ' - '| |\n' - '| | *x* in *s* ' - '| |\n' - '+----------------------------+----------------------------------+------------+\n' - '\n' - 'Sequences of the same type also support comparisons. In ' - 'particular,\n' - 'tuples and lists are compared lexicographically by comparing\n' - 'corresponding elements. This means that to compare equal, every\n' - 'element must compare equal and the two sequences must be of the ' - 'same\n' - 'type and have the same length. (For full details see ' - 'Comparisons in\n' - 'the language reference.)\n' - '\n' - 'Forward and reversed iterators over mutable sequences access ' - 'values\n' - 'using an index. That index will continue to march forward (or\n' - 'backward) even if the underlying sequence is mutated. The ' - 'iterator\n' - 'terminates only when an "IndexError" or a "StopIteration" is\n' - 'encountered (or when the index drops below zero).\n' - '\n' - 'Notes:\n' - '\n' - '1. While the "in" and "not in" operations are used only for ' - 'simple\n' - ' containment testing in the general case, some specialised ' - 'sequences\n' - ' (such as "str", "bytes" and "bytearray") also use them for\n' - ' subsequence testing:\n' - '\n' - ' >>> "gg" in "eggs"\n' - ' True\n' - '\n' - '2. Values of *n* less than "0" are treated as "0" (which yields ' - 'an\n' - ' empty sequence of the same type as *s*). Note that items in ' - 'the\n' - ' sequence *s* are not copied; they are referenced multiple ' - 'times.\n' - ' This often haunts new Python programmers; consider:\n' - '\n' - ' >>> lists = [[]] * 3\n' - ' >>> lists\n' - ' [[], [], []]\n' - ' >>> lists[0].append(3)\n' - ' >>> lists\n' - ' [[3], [3], [3]]\n' - '\n' - ' What has happened is that "[[]]" is a one-element list ' - 'containing\n' - ' an empty list, so all three elements of "[[]] * 3" are ' - 'references\n' - ' to this single empty list. Modifying any of the elements of\n' - ' "lists" modifies this single list. You can create a list of\n' - ' different lists this way:\n' - '\n' - ' >>> lists = [[] for i in range(3)]\n' - ' >>> lists[0].append(3)\n' - ' >>> lists[1].append(5)\n' - ' >>> lists[2].append(7)\n' - ' >>> lists\n' - ' [[3], [5], [7]]\n' - '\n' - ' Further explanation is available in the FAQ entry How do I ' - 'create a\n' - ' multidimensional list?.\n' - '\n' - '3. If *i* or *j* is negative, the index is relative to the end ' - 'of\n' - ' sequence *s*: "len(s) + i" or "len(s) + j" is substituted. ' - 'But\n' - ' note that "-0" is still "0".\n' - '\n' - '4. The slice of *s* from *i* to *j* is defined as the sequence ' - 'of\n' - ' items with index *k* such that "i <= k < j". If *i* or *j* ' - 'is\n' - ' greater than "len(s)", use "len(s)". If *i* is omitted or ' - '"None",\n' - ' use "0". If *j* is omitted or "None", use "len(s)". If *i* ' - 'is\n' - ' greater than or equal to *j*, the slice is empty.\n' - '\n' - '5. The slice of *s* from *i* to *j* with step *k* is defined as ' - 'the\n' - ' sequence of items with index "x = i + n*k" such that "0 <= n ' - '<\n' - ' (j-i)/k". In other words, the indices are "i", "i+k", ' - '"i+2*k",\n' - ' "i+3*k" and so on, stopping when *j* is reached (but never\n' - ' including *j*). When *k* is positive, *i* and *j* are ' - 'reduced to\n' - ' "len(s)" if they are greater. When *k* is negative, *i* and ' - '*j* are\n' - ' reduced to "len(s) - 1" if they are greater. If *i* or *j* ' - 'are\n' - ' omitted or "None", they become “end” values (which end ' - 'depends on\n' - ' the sign of *k*). Note, *k* cannot be zero. If *k* is ' - '"None", it\n' - ' is treated like "1".\n' - '\n' - '6. Concatenating immutable sequences always results in a new ' - 'object.\n' - ' This means that building up a sequence by repeated ' - 'concatenation\n' - ' will have a quadratic runtime cost in the total sequence ' - 'length.\n' - ' To get a linear runtime cost, you must switch to one of the\n' - ' alternatives below:\n' - '\n' - ' * if concatenating "str" objects, you can build a list and ' - 'use\n' - ' "str.join()" at the end or else write to an "io.StringIO"\n' - ' instance and retrieve its value when complete\n' - '\n' - ' * if concatenating "bytes" objects, you can similarly use\n' - ' "bytes.join()" or "io.BytesIO", or you can do in-place\n' - ' concatenation with a "bytearray" object. "bytearray" ' - 'objects are\n' - ' mutable and have an efficient overallocation mechanism\n' - '\n' - ' * if concatenating "tuple" objects, extend a "list" instead\n' - '\n' - ' * for other types, investigate the relevant class ' - 'documentation\n' - '\n' - '7. Some sequence types (such as "range") only support item ' - 'sequences\n' - ' that follow specific patterns, and hence don’t support ' - 'sequence\n' - ' concatenation or repetition.\n' - '\n' - '8. "index" raises "ValueError" when *x* is not found in *s*. Not ' - 'all\n' - ' implementations support passing the additional arguments *i* ' - 'and\n' - ' *j*. These arguments allow efficient searching of subsections ' - 'of\n' - ' the sequence. Passing the extra arguments is roughly ' - 'equivalent to\n' - ' using "s[i:j].index(x)", only without copying any data and ' - 'with the\n' - ' returned index being relative to the start of the sequence ' - 'rather\n' - ' than the start of the slice.\n' - '\n' - '\n' - 'Immutable Sequence Types\n' - '========================\n' - '\n' - 'The only operation that immutable sequence types generally ' - 'implement\n' - 'that is not also implemented by mutable sequence types is ' - 'support for\n' - 'the "hash()" built-in.\n' - '\n' - 'This support allows immutable sequences, such as "tuple" ' - 'instances, to\n' - 'be used as "dict" keys and stored in "set" and "frozenset" ' - 'instances.\n' - '\n' - 'Attempting to hash an immutable sequence that contains ' - 'unhashable\n' - 'values will result in "TypeError".\n' - '\n' - '\n' - 'Mutable Sequence Types\n' - '======================\n' - '\n' - 'The operations in the following table are defined on mutable ' - 'sequence\n' - 'types. The "collections.abc.MutableSequence" ABC is provided to ' - 'make\n' - 'it easier to correctly implement these operations on custom ' - 'sequence\n' - 'types.\n' - '\n' - 'In the table *s* is an instance of a mutable sequence type, *t* ' - 'is any\n' - 'iterable object and *x* is an arbitrary object that meets any ' - 'type and\n' - 'value restrictions imposed by *s* (for example, "bytearray" ' - 'only\n' - 'accepts integers that meet the value restriction "0 <= x <= ' - '255").\n' - '\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '| Operation | ' - 'Result | Notes |\n' - '|================================|==================================|=======================|\n' - '| "s[i] = x" | item *i* of *s* is replaced ' - 'by | |\n' - '| | ' - '*x* | |\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '| "s[i:j] = t" | slice of *s* from *i* to *j* ' - 'is | |\n' - '| | replaced by the contents of ' - 'the | |\n' - '| | iterable ' - '*t* | |\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '| "del s[i:j]" | same as "s[i:j] = ' - '[]" | |\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '| "s[i:j:k] = t" | the elements of "s[i:j:k]" ' - 'are | (1) |\n' - '| | replaced by those of ' - '*t* | |\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '| "del s[i:j:k]" | removes the elements ' - 'of | |\n' - '| | "s[i:j:k]" from the ' - 'list | |\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '| "s.append(x)" | appends *x* to the end of ' - 'the | |\n' - '| | sequence (same ' - 'as | |\n' - '| | "s[len(s):len(s)] = ' - '[x]") | |\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '| "s.clear()" | removes all items from *s* ' - '(same | (5) |\n' - '| | as "del ' - 's[:]") | |\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '| "s.copy()" | creates a shallow copy of ' - '*s* | (5) |\n' - '| | (same as ' - '"s[:]") | |\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '| "s.extend(t)" or "s += t" | extends *s* with the contents ' - 'of | |\n' - '| | *t* (for the most part the ' - 'same | |\n' - '| | as "s[len(s):len(s)] = ' - 't") | |\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '| "s *= n" | updates *s* with its ' - 'contents | (6) |\n' - '| | repeated *n* ' - 'times | |\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '| "s.insert(i, x)" | inserts *x* into *s* at ' - 'the | |\n' - '| | index given by *i* (same ' - 'as | |\n' - '| | "s[i:i] = ' - '[x]") | |\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '| "s.pop()" or "s.pop(i)" | retrieves the item at *i* ' - 'and | (2) |\n' - '| | also removes it from ' - '*s* | |\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '| "s.remove(x)" | remove the first item from ' - '*s* | (3) |\n' - '| | where "s[i]" is equal to ' - '*x* | |\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '| "s.reverse()" | reverses the items of *s* ' - 'in | (4) |\n' - '| | ' - 'place | |\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '\n' - 'Notes:\n' - '\n' - '1. *t* must have the same length as the slice it is replacing.\n' - '\n' - '2. The optional argument *i* defaults to "-1", so that by ' - 'default the\n' - ' last item is removed and returned.\n' - '\n' - '3. "remove()" raises "ValueError" when *x* is not found in *s*.\n' - '\n' - '4. The "reverse()" method modifies the sequence in place for ' - 'economy\n' - ' of space when reversing a large sequence. To remind users ' - 'that it\n' - ' operates by side effect, it does not return the reversed ' - 'sequence.\n' - '\n' - '5. "clear()" and "copy()" are included for consistency with the\n' - ' interfaces of mutable containers that don’t support slicing\n' - ' operations (such as "dict" and "set"). "copy()" is not part ' - 'of the\n' - ' "collections.abc.MutableSequence" ABC, but most concrete ' - 'mutable\n' - ' sequence classes provide it.\n' - '\n' - ' New in version 3.3: "clear()" and "copy()" methods.\n' - '\n' - '6. The value *n* is an integer, or an object implementing\n' - ' "__index__()". Zero and negative values of *n* clear the ' - 'sequence.\n' - ' Items in the sequence are not copied; they are referenced ' - 'multiple\n' - ' times, as explained for "s * n" under Common Sequence ' - 'Operations.\n' - '\n' - '\n' - 'Lists\n' - '=====\n' - '\n' - 'Lists are mutable sequences, typically used to store collections ' - 'of\n' - 'homogeneous items (where the precise degree of similarity will ' - 'vary by\n' - 'application).\n' - '\n' - 'class list([iterable])\n' - '\n' - ' Lists may be constructed in several ways:\n' - '\n' - ' * Using a pair of square brackets to denote the empty list: ' - '"[]"\n' - '\n' - ' * Using square brackets, separating items with commas: "[a]", ' - '"[a,\n' - ' b, c]"\n' - '\n' - ' * Using a list comprehension: "[x for x in iterable]"\n' - '\n' - ' * Using the type constructor: "list()" or "list(iterable)"\n' - '\n' - ' The constructor builds a list whose items are the same and in ' - 'the\n' - ' same order as *iterable*’s items. *iterable* may be either ' - 'a\n' - ' sequence, a container that supports iteration, or an ' - 'iterator\n' - ' object. If *iterable* is already a list, a copy is made and\n' - ' returned, similar to "iterable[:]". For example, ' - '"list(\'abc\')"\n' - ' returns "[\'a\', \'b\', \'c\']" and "list( (1, 2, 3) )" ' - 'returns "[1, 2,\n' - ' 3]". If no argument is given, the constructor creates a new ' - 'empty\n' - ' list, "[]".\n' - '\n' - ' Many other operations also produce lists, including the ' - '"sorted()"\n' - ' built-in.\n' - '\n' - ' Lists implement all of the common and mutable sequence ' - 'operations.\n' - ' Lists also provide the following additional method:\n' - '\n' - ' sort(*, key=None, reverse=False)\n' - '\n' - ' This method sorts the list in place, using only "<" ' - 'comparisons\n' - ' between items. Exceptions are not suppressed - if any ' - 'comparison\n' - ' operations fail, the entire sort operation will fail (and ' - 'the\n' - ' list will likely be left in a partially modified state).\n' - '\n' - ' "sort()" accepts two arguments that can only be passed by\n' - ' keyword (keyword-only arguments):\n' - '\n' - ' *key* specifies a function of one argument that is used ' - 'to\n' - ' extract a comparison key from each list element (for ' - 'example,\n' - ' "key=str.lower"). The key corresponding to each item in ' - 'the list\n' - ' is calculated once and then used for the entire sorting ' - 'process.\n' - ' The default value of "None" means that list items are ' - 'sorted\n' - ' directly without calculating a separate key value.\n' - '\n' - ' The "functools.cmp_to_key()" utility is available to ' - 'convert a\n' - ' 2.x style *cmp* function to a *key* function.\n' - '\n' - ' *reverse* is a boolean value. If set to "True", then the ' - 'list\n' - ' elements are sorted as if each comparison were reversed.\n' - '\n' - ' This method modifies the sequence in place for economy of ' - 'space\n' - ' when sorting a large sequence. To remind users that it ' - 'operates\n' - ' by side effect, it does not return the sorted sequence ' - '(use\n' - ' "sorted()" to explicitly request a new sorted list ' - 'instance).\n' - '\n' - ' The "sort()" method is guaranteed to be stable. A sort ' - 'is\n' - ' stable if it guarantees not to change the relative order ' - 'of\n' - ' elements that compare equal — this is helpful for sorting ' - 'in\n' - ' multiple passes (for example, sort by department, then by ' - 'salary\n' - ' grade).\n' - '\n' - ' For sorting examples and a brief sorting tutorial, see ' - 'Sorting\n' - ' HOW TO.\n' - '\n' - ' **CPython implementation detail:** While a list is being ' - 'sorted,\n' - ' the effect of attempting to mutate, or even inspect, the ' - 'list is\n' - ' undefined. The C implementation of Python makes the list ' - 'appear\n' - ' empty for the duration, and raises "ValueError" if it can ' - 'detect\n' - ' that the list has been mutated during a sort.\n' - '\n' - '\n' - 'Tuples\n' - '======\n' - '\n' - 'Tuples are immutable sequences, typically used to store ' - 'collections of\n' - 'heterogeneous data (such as the 2-tuples produced by the ' - '"enumerate()"\n' - 'built-in). Tuples are also used for cases where an immutable ' - 'sequence\n' - 'of homogeneous data is needed (such as allowing storage in a ' - '"set" or\n' - '"dict" instance).\n' - '\n' - 'class tuple([iterable])\n' - '\n' - ' Tuples may be constructed in a number of ways:\n' - '\n' - ' * Using a pair of parentheses to denote the empty tuple: ' - '"()"\n' - '\n' - ' * Using a trailing comma for a singleton tuple: "a," or ' - '"(a,)"\n' - '\n' - ' * Separating items with commas: "a, b, c" or "(a, b, c)"\n' - '\n' - ' * Using the "tuple()" built-in: "tuple()" or ' - '"tuple(iterable)"\n' - '\n' - ' The constructor builds a tuple whose items are the same and ' - 'in the\n' - ' same order as *iterable*’s items. *iterable* may be either ' - 'a\n' - ' sequence, a container that supports iteration, or an ' - 'iterator\n' - ' object. If *iterable* is already a tuple, it is returned\n' - ' unchanged. For example, "tuple(\'abc\')" returns "(\'a\', ' - '\'b\', \'c\')"\n' - ' and "tuple( [1, 2, 3] )" returns "(1, 2, 3)". If no argument ' - 'is\n' - ' given, the constructor creates a new empty tuple, "()".\n' - '\n' - ' Note that it is actually the comma which makes a tuple, not ' - 'the\n' - ' parentheses. The parentheses are optional, except in the ' - 'empty\n' - ' tuple case, or when they are needed to avoid syntactic ' - 'ambiguity.\n' - ' For example, "f(a, b, c)" is a function call with three ' - 'arguments,\n' - ' while "f((a, b, c))" is a function call with a 3-tuple as the ' - 'sole\n' - ' argument.\n' - '\n' - ' Tuples implement all of the common sequence operations.\n' - '\n' - 'For heterogeneous collections of data where access by name is ' - 'clearer\n' - 'than access by index, "collections.namedtuple()" may be a more\n' - 'appropriate choice than a simple tuple object.\n' - '\n' - '\n' - 'Ranges\n' - '======\n' - '\n' - 'The "range" type represents an immutable sequence of numbers and ' - 'is\n' - 'commonly used for looping a specific number of times in "for" ' - 'loops.\n' - '\n' - 'class range(stop)\n' - 'class range(start, stop[, step])\n' - '\n' - ' The arguments to the range constructor must be integers ' - '(either\n' - ' built-in "int" or any object that implements the ' - '"__index__()"\n' - ' special method). If the *step* argument is omitted, it ' - 'defaults to\n' - ' "1". If the *start* argument is omitted, it defaults to "0". ' - 'If\n' - ' *step* is zero, "ValueError" is raised.\n' - '\n' - ' For a positive *step*, the contents of a range "r" are ' - 'determined\n' - ' by the formula "r[i] = start + step*i" where "i >= 0" and ' - '"r[i] <\n' - ' stop".\n' - '\n' - ' For a negative *step*, the contents of the range are still\n' - ' determined by the formula "r[i] = start + step*i", but the\n' - ' constraints are "i >= 0" and "r[i] > stop".\n' - '\n' - ' A range object will be empty if "r[0]" does not meet the ' - 'value\n' - ' constraint. Ranges do support negative indices, but these ' - 'are\n' - ' interpreted as indexing from the end of the sequence ' - 'determined by\n' - ' the positive indices.\n' - '\n' - ' Ranges containing absolute values larger than "sys.maxsize" ' - 'are\n' - ' permitted but some features (such as "len()") may raise\n' - ' "OverflowError".\n' - '\n' - ' Range examples:\n' - '\n' - ' >>> list(range(10))\n' - ' [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]\n' - ' >>> list(range(1, 11))\n' - ' [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]\n' - ' >>> list(range(0, 30, 5))\n' - ' [0, 5, 10, 15, 20, 25]\n' - ' >>> list(range(0, 10, 3))\n' - ' [0, 3, 6, 9]\n' - ' >>> list(range(0, -10, -1))\n' - ' [0, -1, -2, -3, -4, -5, -6, -7, -8, -9]\n' - ' >>> list(range(0))\n' - ' []\n' - ' >>> list(range(1, 0))\n' - ' []\n' - '\n' - ' Ranges implement all of the common sequence operations ' - 'except\n' - ' concatenation and repetition (due to the fact that range ' - 'objects\n' - ' can only represent sequences that follow a strict pattern ' - 'and\n' - ' repetition and concatenation will usually violate that ' - 'pattern).\n' - '\n' - ' start\n' - '\n' - ' The value of the *start* parameter (or "0" if the ' - 'parameter was\n' - ' not supplied)\n' - '\n' - ' stop\n' - '\n' - ' The value of the *stop* parameter\n' - '\n' - ' step\n' - '\n' - ' The value of the *step* parameter (or "1" if the parameter ' - 'was\n' - ' not supplied)\n' - '\n' - 'The advantage of the "range" type over a regular "list" or ' - '"tuple" is\n' - 'that a "range" object will always take the same (small) amount ' - 'of\n' - 'memory, no matter the size of the range it represents (as it ' - 'only\n' - 'stores the "start", "stop" and "step" values, calculating ' - 'individual\n' - 'items and subranges as needed).\n' - '\n' - 'Range objects implement the "collections.abc.Sequence" ABC, and\n' - 'provide features such as containment tests, element index ' - 'lookup,\n' - 'slicing and support for negative indices (see Sequence Types — ' - 'list,\n' - 'tuple, range):\n' - '\n' - '>>> r = range(0, 20, 2)\n' - '>>> r\n' - 'range(0, 20, 2)\n' - '>>> 11 in r\n' - 'False\n' - '>>> 10 in r\n' - 'True\n' - '>>> r.index(10)\n' - '5\n' - '>>> r[5]\n' - '10\n' - '>>> r[:5]\n' - 'range(0, 10, 2)\n' - '>>> r[-1]\n' - '18\n' - '\n' - 'Testing range objects for equality with "==" and "!=" compares ' - 'them as\n' - 'sequences. That is, two range objects are considered equal if ' - 'they\n' - 'represent the same sequence of values. (Note that two range ' - 'objects\n' - 'that compare equal might have different "start", "stop" and ' - '"step"\n' - 'attributes, for example "range(0) == range(2, 1, 3)" or ' - '"range(0, 3,\n' - '2) == range(0, 4, 2)".)\n' - '\n' - 'Changed in version 3.2: Implement the Sequence ABC. Support ' - 'slicing\n' - 'and negative indices. Test "int" objects for membership in ' - 'constant\n' - 'time instead of iterating through all items.\n' - '\n' - 'Changed in version 3.3: Define ‘==’ and ‘!=’ to compare range ' - 'objects\n' - 'based on the sequence of values they define (instead of ' - 'comparing\n' - 'based on object identity).\n' - '\n' - 'New in version 3.3: The "start", "stop" and "step" attributes.\n' - '\n' - 'See also:\n' - '\n' - ' * The linspace recipe shows how to implement a lazy version of ' - 'range\n' - ' suitable for floating point applications.\n', - 'typesseq-mutable': 'Mutable Sequence Types\n' - '**********************\n' - '\n' - 'The operations in the following table are defined on ' - 'mutable sequence\n' - 'types. The "collections.abc.MutableSequence" ABC is ' - 'provided to make\n' - 'it easier to correctly implement these operations on ' - 'custom sequence\n' - 'types.\n' - '\n' - 'In the table *s* is an instance of a mutable sequence ' - 'type, *t* is any\n' - 'iterable object and *x* is an arbitrary object that ' - 'meets any type and\n' - 'value restrictions imposed by *s* (for example, ' - '"bytearray" only\n' - 'accepts integers that meet the value restriction "0 <= x ' - '<= 255").\n' - '\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '| Operation | ' - 'Result | Notes ' - '|\n' - '|================================|==================================|=======================|\n' - '| "s[i] = x" | item *i* of *s* is ' - 'replaced by | |\n' - '| | ' - '*x* | ' - '|\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '| "s[i:j] = t" | slice of *s* from *i* ' - 'to *j* is | |\n' - '| | replaced by the ' - 'contents of the | |\n' - '| | iterable ' - '*t* | |\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '| "del s[i:j]" | same as "s[i:j] = ' - '[]" | |\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '| "s[i:j:k] = t" | the elements of ' - '"s[i:j:k]" are | (1) |\n' - '| | replaced by those of ' - '*t* | |\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '| "del s[i:j:k]" | removes the elements ' - 'of | |\n' - '| | "s[i:j:k]" from the ' - 'list | |\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '| "s.append(x)" | appends *x* to the ' - 'end of the | |\n' - '| | sequence (same ' - 'as | |\n' - '| | "s[len(s):len(s)] = ' - '[x]") | |\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '| "s.clear()" | removes all items ' - 'from *s* (same | (5) |\n' - '| | as "del ' - 's[:]") | |\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '| "s.copy()" | creates a shallow ' - 'copy of *s* | (5) |\n' - '| | (same as ' - '"s[:]") | |\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '| "s.extend(t)" or "s += t" | extends *s* with the ' - 'contents of | |\n' - '| | *t* (for the most ' - 'part the same | |\n' - '| | as "s[len(s):len(s)] ' - '= t") | |\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '| "s *= n" | updates *s* with its ' - 'contents | (6) |\n' - '| | repeated *n* ' - 'times | |\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '| "s.insert(i, x)" | inserts *x* into *s* ' - 'at the | |\n' - '| | index given by *i* ' - '(same as | |\n' - '| | "s[i:i] = ' - '[x]") | |\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '| "s.pop()" or "s.pop(i)" | retrieves the item at ' - '*i* and | (2) |\n' - '| | also removes it from ' - '*s* | |\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '| "s.remove(x)" | remove the first item ' - 'from *s* | (3) |\n' - '| | where "s[i]" is equal ' - 'to *x* | |\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '| "s.reverse()" | reverses the items of ' - '*s* in | (4) |\n' - '| | ' - 'place | ' - '|\n' - '+--------------------------------+----------------------------------+-----------------------+\n' - '\n' - 'Notes:\n' - '\n' - '1. *t* must have the same length as the slice it is ' - 'replacing.\n' - '\n' - '2. The optional argument *i* defaults to "-1", so that ' - 'by default the\n' - ' last item is removed and returned.\n' - '\n' - '3. "remove()" raises "ValueError" when *x* is not found ' - 'in *s*.\n' - '\n' - '4. The "reverse()" method modifies the sequence in place ' - 'for economy\n' - ' of space when reversing a large sequence. To remind ' - 'users that it\n' - ' operates by side effect, it does not return the ' - 'reversed sequence.\n' - '\n' - '5. "clear()" and "copy()" are included for consistency ' - 'with the\n' - ' interfaces of mutable containers that don’t support ' - 'slicing\n' - ' operations (such as "dict" and "set"). "copy()" is ' - 'not part of the\n' - ' "collections.abc.MutableSequence" ABC, but most ' - 'concrete mutable\n' - ' sequence classes provide it.\n' - '\n' - ' New in version 3.3: "clear()" and "copy()" methods.\n' - '\n' - '6. The value *n* is an integer, or an object ' - 'implementing\n' - ' "__index__()". Zero and negative values of *n* clear ' - 'the sequence.\n' - ' Items in the sequence are not copied; they are ' - 'referenced multiple\n' - ' times, as explained for "s * n" under Common Sequence ' - 'Operations.\n', - 'unary': 'Unary arithmetic and bitwise operations\n' - '***************************************\n' - '\n' - 'All unary arithmetic and bitwise operations have the same ' - 'priority:\n' - '\n' - ' u_expr ::= power | "-" u_expr | "+" u_expr | "~" u_expr\n' - '\n' - 'The unary "-" (minus) operator yields the negation of its numeric\n' - 'argument; the operation can be overridden with the "__neg__()" ' - 'special\n' - 'method.\n' - '\n' - 'The unary "+" (plus) operator yields its numeric argument ' - 'unchanged;\n' - 'the operation can be overridden with the "__pos__()" special ' - 'method.\n' - '\n' - 'The unary "~" (invert) operator yields the bitwise inversion of ' - 'its\n' - 'integer argument. The bitwise inversion of "x" is defined as\n' - '"-(x+1)". It only applies to integral numbers or to custom ' - 'objects\n' - 'that override the "__invert__()" special method.\n' - '\n' - 'In all three cases, if the argument does not have the proper type, ' - 'a\n' - '"TypeError" exception is raised.\n', - 'while': 'The "while" statement\n' - '*********************\n' - '\n' - 'The "while" statement is used for repeated execution as long as an\n' - 'expression is true:\n' - '\n' - ' while_stmt ::= "while" assignment_expression ":" suite\n' - ' ["else" ":" suite]\n' - '\n' - 'This repeatedly tests the expression and, if it is true, executes ' - 'the\n' - 'first suite; if the expression is false (which may be the first ' - 'time\n' - 'it is tested) the suite of the "else" clause, if present, is ' - 'executed\n' - 'and the loop terminates.\n' - '\n' - 'A "break" statement executed in the first suite terminates the ' - 'loop\n' - 'without executing the "else" clause’s suite. A "continue" ' - 'statement\n' - 'executed in the first suite skips the rest of the suite and goes ' - 'back\n' - 'to testing the expression.\n', - 'with': 'The "with" statement\n' - '********************\n' - '\n' - 'The "with" statement is used to wrap the execution of a block with\n' - 'methods defined by a context manager (see section With Statement\n' - 'Context Managers). This allows common "try"…"except"…"finally" ' - 'usage\n' - 'patterns to be encapsulated for convenient reuse.\n' - '\n' - ' with_stmt ::= "with" ( "(" with_stmt_contents ","? ")" | ' - 'with_stmt_contents ) ":" suite\n' - ' with_stmt_contents ::= with_item ("," with_item)*\n' - ' with_item ::= expression ["as" target]\n' - '\n' - 'The execution of the "with" statement with one “item” proceeds as\n' - 'follows:\n' - '\n' - '1. The context expression (the expression given in the "with_item") ' - 'is\n' - ' evaluated to obtain a context manager.\n' - '\n' - '2. The context manager’s "__enter__()" is loaded for later use.\n' - '\n' - '3. The context manager’s "__exit__()" is loaded for later use.\n' - '\n' - '4. The context manager’s "__enter__()" method is invoked.\n' - '\n' - '5. If a target was included in the "with" statement, the return ' - 'value\n' - ' from "__enter__()" is assigned to it.\n' - '\n' - ' Note:\n' - '\n' - ' The "with" statement guarantees that if the "__enter__()" ' - 'method\n' - ' returns without an error, then "__exit__()" will always be\n' - ' called. Thus, if an error occurs during the assignment to the\n' - ' target list, it will be treated the same as an error occurring\n' - ' within the suite would be. See step 6 below.\n' - '\n' - '6. The suite is executed.\n' - '\n' - '7. The context manager’s "__exit__()" method is invoked. If an\n' - ' exception caused the suite to be exited, its type, value, and\n' - ' traceback are passed as arguments to "__exit__()". Otherwise, ' - 'three\n' - ' "None" arguments are supplied.\n' - '\n' - ' If the suite was exited due to an exception, and the return ' - 'value\n' - ' from the "__exit__()" method was false, the exception is ' - 'reraised.\n' - ' If the return value was true, the exception is suppressed, and\n' - ' execution continues with the statement following the "with"\n' - ' statement.\n' - '\n' - ' If the suite was exited for any reason other than an exception, ' - 'the\n' - ' return value from "__exit__()" is ignored, and execution ' - 'proceeds\n' - ' at the normal location for the kind of exit that was taken.\n' - '\n' - 'The following code:\n' - '\n' - ' with EXPRESSION as TARGET:\n' - ' SUITE\n' - '\n' - 'is semantically equivalent to:\n' - '\n' - ' manager = (EXPRESSION)\n' - ' enter = type(manager).__enter__\n' - ' exit = type(manager).__exit__\n' - ' value = enter(manager)\n' - ' hit_except = False\n' - '\n' - ' try:\n' - ' TARGET = value\n' - ' SUITE\n' - ' except:\n' - ' hit_except = True\n' - ' if not exit(manager, *sys.exc_info()):\n' - ' raise\n' - ' finally:\n' - ' if not hit_except:\n' - ' exit(manager, None, None, None)\n' - '\n' - 'With more than one item, the context managers are processed as if\n' - 'multiple "with" statements were nested:\n' - '\n' - ' with A() as a, B() as b:\n' - ' SUITE\n' - '\n' - 'is semantically equivalent to:\n' - '\n' - ' with A() as a:\n' - ' with B() as b:\n' - ' SUITE\n' - '\n' - 'You can also write multi-item context managers in multiple lines if\n' - 'the items are surrounded by parentheses. For example:\n' - '\n' - ' with (\n' - ' A() as a,\n' - ' B() as b,\n' - ' ):\n' - ' SUITE\n' - '\n' - 'Changed in version 3.1: Support for multiple context expressions.\n' - '\n' - 'Changed in version 3.10: Support for using grouping parentheses to\n' - 'break the statement in multiple lines.\n' - '\n' - 'See also:\n' - '\n' - ' **PEP 343** - The “with” statement\n' - ' The specification, background, and examples for the Python ' - '"with"\n' - ' statement.\n', - 'yield': 'The "yield" statement\n' - '*********************\n' - '\n' - ' yield_stmt ::= yield_expression\n' - '\n' - 'A "yield" statement is semantically equivalent to a yield ' - 'expression.\n' - 'The yield statement can be used to omit the parentheses that would\n' - 'otherwise be required in the equivalent yield expression ' - 'statement.\n' - 'For example, the yield statements\n' - '\n' - ' yield <expr>\n' - ' yield from <expr>\n' - '\n' - 'are equivalent to the yield expression statements\n' - '\n' - ' (yield <expr>)\n' - ' (yield from <expr>)\n' - '\n' - 'Yield expressions and statements are only used when defining a\n' - '*generator* function, and are only used in the body of the ' - 'generator\n' - 'function. Using yield in a function definition is sufficient to ' - 'cause\n' - 'that definition to create a generator function instead of a normal\n' - 'function.\n' - '\n' - 'For full details of "yield" semantics, refer to the Yield ' - 'expressions\n' - 'section.\n'} |