oss ydb: fix dstool building and test run

2 files changed, 1747 insertions, 0 deletions

diff --git a/contrib/deprecated/python/configparser/backports/configparser/__init__.py b/contrib/deprecated/python/configparser/backports/configparser/__init__.py
new file mode 100644
index 00000000000..603d6047640
--- /dev/null
+++ b/contrib/deprecated/python/configparser/backports/configparser/__init__.py
@@ -0,0 +1,1473 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+# flake8: noqa
+
+"""Configuration file parser.
+
+A configuration file consists of sections, lead by a "[section]" header,
+and followed by "name: value" entries, with continuations and such in
+the style of RFC 822.
+
+Intrinsic defaults can be specified by passing them into the
+ConfigParser constructor as a dictionary.
+
+class:
+
+ConfigParser -- responsible for parsing a list of
+                    configuration files, and managing the parsed database.
+
+    methods:
+
+    __init__(defaults=None, dict_type=_default_dict, allow_no_value=False,
+             delimiters=('=', ':'), comment_prefixes=('#', ';'),
+             inline_comment_prefixes=None, strict=True,
+             empty_lines_in_values=True, default_section='DEFAULT',
+             interpolation=<unset>, converters=<unset>):
+        Create the parser. When `defaults' is given, it is initialized into the
+        dictionary or intrinsic defaults. The keys must be strings, the values
+        must be appropriate for %()s string interpolation.
+
+        When `dict_type' is given, it will be used to create the dictionary
+        objects for the list of sections, for the options within a section, and
+        for the default values.
+
+        When `delimiters' is given, it will be used as the set of substrings
+        that divide keys from values.
+
+        When `comment_prefixes' is given, it will be used as the set of
+        substrings that prefix comments in empty lines. Comments can be
+        indented.
+
+        When `inline_comment_prefixes' is given, it will be used as the set of
+        substrings that prefix comments in non-empty lines.
+
+        When `strict` is True, the parser won't allow for any section or option
+        duplicates while reading from a single source (file, string or
+        dictionary). Default is True.
+
+        When `empty_lines_in_values' is False (default: True), each empty line
+        marks the end of an option. Otherwise, internal empty lines of
+        a multiline option are kept as part of the value.
+
+        When `allow_no_value' is True (default: False), options without
+        values are accepted; the value presented for these is None.
+
+        When `default_section' is given, the name of the special section is
+        named accordingly. By default it is called ``"DEFAULT"`` but this can
+        be customized to point to any other valid section name. Its current
+        value can be retrieved using the ``parser_instance.default_section``
+        attribute and may be modified at runtime.
+
+        When `interpolation` is given, it should be an Interpolation subclass
+        instance. It will be used as the handler for option value
+        pre-processing when using getters. RawConfigParser objects don't do
+        any sort of interpolation, whereas ConfigParser uses an instance of
+        BasicInterpolation. The library also provides a ``zc.buildbot``
+        inspired ExtendedInterpolation implementation.
+
+        When `converters` is given, it should be a dictionary where each key
+        represents the name of a type converter and each value is a callable
+        implementing the conversion from string to the desired datatype. Every
+        converter gets its corresponding get*() method on the parser object and
+        section proxies.
+
+    sections()
+        Return all the configuration section names, sans DEFAULT.
+
+    has_section(section)
+        Return whether the given section exists.
+
+    has_option(section, option)
+        Return whether the given option exists in the given section.
+
+    options(section)
+        Return list of configuration options for the named section.
+
+    read(filenames, encoding=None)
+        Read and parse the iterable of named configuration files, given by
+        name.  A single filename is also allowed.  Non-existing files
+        are ignored.  Return list of successfully read files.
+
+    read_file(f, filename=None)
+        Read and parse one configuration file, given as a file object.
+        The filename defaults to f.name; it is only used in error
+        messages (if f has no `name' attribute, the string `<???>' is used).
+
+    read_string(string)
+        Read configuration from a given string.
+
+    read_dict(dictionary)
+        Read configuration from a dictionary. Keys are section names,
+        values are dictionaries with keys and values that should be present
+        in the section. If the used dictionary type preserves order, sections
+        and their keys will be added in order. Values are automatically
+        converted to strings.
+
+    get(section, option, raw=False, vars=None, fallback=_UNSET)
+        Return a string value for the named option.  All % interpolations are
+        expanded in the return values, based on the defaults passed into the
+        constructor and the DEFAULT section.  Additional substitutions may be
+        provided using the `vars' argument, which must be a dictionary whose
+        contents override any pre-existing defaults. If `option' is a key in
+        `vars', the value from `vars' is used.
+
+    getint(section, options, raw=False, vars=None, fallback=_UNSET)
+        Like get(), but convert value to an integer.
+
+    getfloat(section, options, raw=False, vars=None, fallback=_UNSET)
+        Like get(), but convert value to a float.
+
+    getboolean(section, options, raw=False, vars=None, fallback=_UNSET)
+        Like get(), but convert value to a boolean (currently case
+        insensitively defined as 0, false, no, off for False, and 1, true,
+        yes, on for True).  Returns False or True.
+
+    items(section=_UNSET, raw=False, vars=None)
+        If section is given, return a list of tuples with (name, value) for
+        each option in the section. Otherwise, return a list of tuples with
+        (section_name, section_proxy) for each section, including DEFAULTSECT.
+
+    remove_section(section)
+        Remove the given file section and all its options.
+
+    remove_option(section, option)
+        Remove the given option from the given section.
+
+    set(section, option, value)
+        Set the given option.
+
+    write(fp, space_around_delimiters=True)
+        Write the configuration state in .ini format. If
+        `space_around_delimiters' is True (the default), delimiters
+        between keys and values are surrounded by spaces.
+"""
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+from __future__ import unicode_literals
+
+try:
+    from collections.abc import MutableMapping
+except ImportError:
+    from collections import MutableMapping
+import functools
+import io
+import itertools
+import os
+import re
+import sys
+import warnings
+
+from backports.configparser.helpers import OrderedDict as _default_dict
+from backports.configparser.helpers import ChainMap as _ChainMap
+from backports.configparser.helpers import from_none, open, str, PY2
+from backports.configparser.helpers import PathLike, fspath
+from backports.configparser.helpers import MutableMapping
+
+__all__ = [
+    "NoSectionError",
+    "DuplicateOptionError",
+    "DuplicateSectionError",
+    "NoOptionError",
+    "InterpolationError",
+    "InterpolationDepthError",
+    "InterpolationMissingOptionError",
+    "InterpolationSyntaxError",
+    "ParsingError",
+    "MissingSectionHeaderError",
+    "ConfigParser",
+    "SafeConfigParser",
+    "RawConfigParser",
+    "Interpolation",
+    "BasicInterpolation",
+    "ExtendedInterpolation",
+    "LegacyInterpolation",
+    "SectionProxy",
+    "ConverterMapping",
+    "DEFAULTSECT",
+    "MAX_INTERPOLATION_DEPTH",
+]
+
+DEFAULTSECT = "DEFAULT"
+
+MAX_INTERPOLATION_DEPTH = 10
+
+
+# exception classes
+class Error(Exception):
+    """Base class for ConfigParser exceptions."""
+
+    def __init__(self, msg=''):
+        self.message = msg
+        Exception.__init__(self, msg)
+
+    def __repr__(self):
+        return self.message
+
+    __str__ = __repr__
+
+
+class NoSectionError(Error):
+    """Raised when no section matches a requested option."""
+
+    def __init__(self, section):
+        Error.__init__(self, 'No section: %r' % (section,))
+        self.section = section
+        self.args = (section,)
+
+
+class DuplicateSectionError(Error):
+    """Raised when a section is repeated in an input source.
+
+    Possible repetitions that raise this exception are: multiple creation
+    using the API or in strict parsers when a section is found more than once
+    in a single input file, string or dictionary.
+    """
+
+    def __init__(self, section, source=None, lineno=None):
+        msg = [repr(section), " already exists"]
+        if source is not None:
+            message = ["While reading from ", repr(source)]
+            if lineno is not None:
+                message.append(" [line {0:2d}]".format(lineno))
+            message.append(": section ")
+            message.extend(msg)
+            msg = message
+        else:
+            msg.insert(0, "Section ")
+        Error.__init__(self, "".join(msg))
+        self.section = section
+        self.source = source
+        self.lineno = lineno
+        self.args = (section, source, lineno)
+
+
+class DuplicateOptionError(Error):
+    """Raised by strict parsers when an option is repeated in an input source.
+
+    Current implementation raises this exception only when an option is found
+    more than once in a single file, string or dictionary.
+    """
+
+    def __init__(self, section, option, source=None, lineno=None):
+        msg = [repr(option), " in section ", repr(section), " already exists"]
+        if source is not None:
+            message = ["While reading from ", repr(source)]
+            if lineno is not None:
+                message.append(" [line {0:2d}]".format(lineno))
+            message.append(": option ")
+            message.extend(msg)
+            msg = message
+        else:
+            msg.insert(0, "Option ")
+        Error.__init__(self, "".join(msg))
+        self.section = section
+        self.option = option
+        self.source = source
+        self.lineno = lineno
+        self.args = (section, option, source, lineno)
+
+
+class NoOptionError(Error):
+    """A requested option was not found."""
+
+    def __init__(self, option, section):
+        Error.__init__(self, "No option %r in section: %r" % (option, section))
+        self.option = option
+        self.section = section
+        self.args = (option, section)
+
+
+class InterpolationError(Error):
+    """Base class for interpolation-related exceptions."""
+
+    def __init__(self, option, section, msg):
+        Error.__init__(self, msg)
+        self.option = option
+        self.section = section
+        self.args = (option, section, msg)
+
+
+class InterpolationMissingOptionError(InterpolationError):
+    """A string substitution required a setting which was not available."""
+
+    def __init__(self, option, section, rawval, reference):
+        msg = (
+            "Bad value substitution: option {0!r} in section {1!r} contains "
+            "an interpolation key {2!r} which is not a valid option name. "
+            "Raw value: {3!r}".format(option, section, reference, rawval)
+        )
+        InterpolationError.__init__(self, option, section, msg)
+        self.reference = reference
+        self.args = (option, section, rawval, reference)
+
+
+class InterpolationSyntaxError(InterpolationError):
+    """Raised when the source text contains invalid syntax.
+
+    Current implementation raises this exception when the source text into
+    which substitutions are made does not conform to the required syntax.
+    """
+
+
+class InterpolationDepthError(InterpolationError):
+    """Raised when substitutions are nested too deeply."""
+
+    def __init__(self, option, section, rawval):
+        msg = (
+            "Recursion limit exceeded in value substitution: option {0!r} "
+            "in section {1!r} contains an interpolation key which "
+            "cannot be substituted in {2} steps. Raw value: {3!r}"
+            "".format(option, section, MAX_INTERPOLATION_DEPTH, rawval)
+        )
+        InterpolationError.__init__(self, option, section, msg)
+        self.args = (option, section, rawval)
+
+
+class ParsingError(Error):
+    """Raised when a configuration file does not follow legal syntax."""
+
+    def __init__(self, source=None, filename=None):
+        # Exactly one of `source'/`filename' arguments has to be given.
+        # `filename' kept for compatibility.
+        if filename and source:
+            raise ValueError(
+                "Cannot specify both `filename' and `source'. " "Use `source'."
+            )
+        elif not filename and not source:
+            raise ValueError("Required argument `source' not given.")
+        elif filename:
+            source = filename
+        Error.__init__(self, 'Source contains parsing errors: %r' % source)
+        self.source = source
+        self.errors = []
+        self.args = (source,)
+
+    @property
+    def filename(self):
+        """Deprecated, use `source'."""
+        warnings.warn(
+            "The 'filename' attribute will be removed in future versions.  "
+            "Use 'source' instead.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        return self.source
+
+    @filename.setter
+    def filename(self, value):
+        """Deprecated, user `source'."""
+        warnings.warn(
+            "The 'filename' attribute will be removed in future versions.  "
+            "Use 'source' instead.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        self.source = value
+
+    def append(self, lineno, line):
+        self.errors.append((lineno, line))
+        self.message += '\n\t[line %2d]: %s' % (lineno, line)
+
+
+class MissingSectionHeaderError(ParsingError):
+    """Raised when a key-value pair is found before any section header."""
+
+    def __init__(self, filename, lineno, line):
+        Error.__init__(
+            self,
+            'File contains no section headers.\nfile: %r, line: %d\n%r'
+            % (filename, lineno, line),
+        )
+        self.source = filename
+        self.lineno = lineno
+        self.line = line
+        self.args = (filename, lineno, line)
+
+
+# Used in parser getters to indicate the default behaviour when a specific
+# option is not found it to raise an exception. Created to enable `None' as
+# a valid fallback value.
+_UNSET = object()
+
+
+class Interpolation(object):
+    """Dummy interpolation that passes the value through with no changes."""
+
+    def before_get(self, parser, section, option, value, defaults):
+        return value
+
+    def before_set(self, parser, section, option, value):
+        return value
+
+    def before_read(self, parser, section, option, value):
+        return value
+
+    def before_write(self, parser, section, option, value):
+        return value
+
+
+class BasicInterpolation(Interpolation):
+    """Interpolation as implemented in the classic ConfigParser.
+
+    The option values can contain format strings which refer to other values in
+    the same section, or values in the special default section.
+
+    For example:
+
+        something: %(dir)s/whatever
+
+    would resolve the "%(dir)s" to the value of dir.  All reference
+    expansions are done late, on demand. If a user needs to use a bare % in
+    a configuration file, she can escape it by writing %%. Other % usage
+    is considered a user error and raises `InterpolationSyntaxError'."""
+
+    _KEYCRE = re.compile(r"%\(([^)]+)\)s")
+
+    def before_get(self, parser, section, option, value, defaults):
+        L = []
+        self._interpolate_some(parser, option, L, value, section, defaults, 1)
+        return ''.join(L)
+
+    def before_set(self, parser, section, option, value):
+        tmp_value = value.replace('%%', '')  # escaped percent signs
+        tmp_value = self._KEYCRE.sub('', tmp_value)  # valid syntax
+        if '%' in tmp_value:
+            raise ValueError(
+                "invalid interpolation syntax in %r at "
+                "position %d" % (value, tmp_value.find('%'))
+            )
+        return value
+
+    def _interpolate_some(self, parser, option, accum, rest, section, map, depth):
+        rawval = parser.get(section, option, raw=True, fallback=rest)
+        if depth > MAX_INTERPOLATION_DEPTH:
+            raise InterpolationDepthError(option, section, rawval)
+        while rest:
+            p = rest.find("%")
+            if p < 0:
+                accum.append(rest)
+                return
+            if p > 0:
+                accum.append(rest[:p])
+                rest = rest[p:]
+            # p is no longer used
+            c = rest[1:2]
+            if c == "%":
+                accum.append("%")
+                rest = rest[2:]
+            elif c == "(":
+                m = self._KEYCRE.match(rest)
+                if m is None:
+                    raise InterpolationSyntaxError(
+                        option,
+                        section,
+                        "bad interpolation variable reference %r" % rest,
+                    )
+                var = parser.optionxform(m.group(1))
+                rest = rest[m.end() :]
+                try:
+                    v = map[var]
+                except KeyError:
+                    raise from_none(
+                        InterpolationMissingOptionError(option, section, rawval, var)
+                    )
+                if "%" in v:
+                    self._interpolate_some(
+                        parser, option, accum, v, section, map, depth + 1
+                    )
+                else:
+                    accum.append(v)
+            else:
+                raise InterpolationSyntaxError(
+                    option,
+                    section,
+                    "'%%' must be followed by '%%' or '(', " "found: %r" % (rest,),
+                )
+
+
+class ExtendedInterpolation(Interpolation):
+    """Advanced variant of interpolation, supports the syntax used by
+    `zc.buildout'. Enables interpolation between sections."""
+
+    _KEYCRE = re.compile(r"\$\{([^}]+)\}")
+
+    def before_get(self, parser, section, option, value, defaults):
+        L = []
+        self._interpolate_some(parser, option, L, value, section, defaults, 1)
+        return ''.join(L)
+
+    def before_set(self, parser, section, option, value):
+        tmp_value = value.replace('$$', '')  # escaped dollar signs
+        tmp_value = self._KEYCRE.sub('', tmp_value)  # valid syntax
+        if '$' in tmp_value:
+            raise ValueError(
+                "invalid interpolation syntax in %r at "
+                "position %d" % (value, tmp_value.find('$'))
+            )
+        return value
+
+    def _interpolate_some(self, parser, option, accum, rest, section, map, depth):
+        rawval = parser.get(section, option, raw=True, fallback=rest)
+        if depth > MAX_INTERPOLATION_DEPTH:
+            raise InterpolationDepthError(option, section, rawval)
+        while rest:
+            p = rest.find("$")
+            if p < 0:
+                accum.append(rest)
+                return
+            if p > 0:
+                accum.append(rest[:p])
+                rest = rest[p:]
+            # p is no longer used
+            c = rest[1:2]
+            if c == "$":
+                accum.append("$")
+                rest = rest[2:]
+            elif c == "{":
+                m = self._KEYCRE.match(rest)
+                if m is None:
+                    raise InterpolationSyntaxError(
+                        option,
+                        section,
+                        "bad interpolation variable reference %r" % rest,
+                    )
+                path = m.group(1).split(':')
+                rest = rest[m.end() :]
+                sect = section
+                opt = option
+                try:
+                    if len(path) == 1:
+                        opt = parser.optionxform(path[0])
+                        v = map[opt]
+                    elif len(path) == 2:
+                        sect = path[0]
+                        opt = parser.optionxform(path[1])
+                        v = parser.get(sect, opt, raw=True)
+                    else:
+                        raise InterpolationSyntaxError(
+                            option, section, "More than one ':' found: %r" % (rest,)
+                        )
+                except (KeyError, NoSectionError, NoOptionError):
+                    raise from_none(
+                        InterpolationMissingOptionError(
+                            option, section, rawval, ":".join(path)
+                        )
+                    )
+                if "$" in v:
+                    self._interpolate_some(
+                        parser,
+                        opt,
+                        accum,
+                        v,
+                        sect,
+                        dict(parser.items(sect, raw=True)),
+                        depth + 1,
+                    )
+                else:
+                    accum.append(v)
+            else:
+                raise InterpolationSyntaxError(
+                    option,
+                    section,
+                    "'$' must be followed by '$' or '{', " "found: %r" % (rest,),
+                )
+
+
+class LegacyInterpolation(Interpolation):
+    """Deprecated interpolation used in old versions of ConfigParser.
+    Use BasicInterpolation or ExtendedInterpolation instead."""
+
+    _KEYCRE = re.compile(r"%\(([^)]*)\)s|.")
+
+    def before_get(self, parser, section, option, value, vars):
+        rawval = value
+        depth = MAX_INTERPOLATION_DEPTH
+        while depth:  # Loop through this until it's done
+            depth -= 1
+            if value and "%(" in value:
+                replace = functools.partial(self._interpolation_replace, parser=parser)
+                value = self._KEYCRE.sub(replace, value)
+                try:
+                    value = value % vars
+                except KeyError as e:
+                    raise from_none(
+                        InterpolationMissingOptionError(
+                            option, section, rawval, e.args[0]
+                        )
+                    )
+            else:
+                break
+        if value and "%(" in value:
+            raise InterpolationDepthError(option, section, rawval)
+        return value
+
+    def before_set(self, parser, section, option, value):
+        return value
+
+    @staticmethod
+    def _interpolation_replace(match, parser):
+        s = match.group(1)
+        if s is None:
+            return match.group()
+        else:
+            return "%%(%s)s" % parser.optionxform(s)
+
+
+class RawConfigParser(MutableMapping):
+    """ConfigParser that does not do interpolation."""
+
+    # Regular expressions for parsing section headers and options
+    _SECT_TMPL = r"""
+        \[                                 # [
+        (?P<header>[^]]+)                  # very permissive!
+        \]                                 # ]
+        """
+    _OPT_TMPL = r"""
+        (?P<option>.*?)                    # very permissive!
+        \s*(?P<vi>{delim})\s*              # any number of space/tab,
+                                           # followed by any of the
+                                           # allowed delimiters,
+                                           # followed by any space/tab
+        (?P<value>.*)$                     # everything up to eol
+        """
+    _OPT_NV_TMPL = r"""
+        (?P<option>.*?)                    # very permissive!
+        \s*(?:                             # any number of space/tab,
+        (?P<vi>{delim})\s*                 # optionally followed by
+                                           # any of the allowed
+                                           # delimiters, followed by any
+                                           # space/tab
+        (?P<value>.*))?$                   # everything up to eol
+        """
+    # Interpolation algorithm to be used if the user does not specify another
+    _DEFAULT_INTERPOLATION = Interpolation()
+    # Compiled regular expression for matching sections
+    SECTCRE = re.compile(_SECT_TMPL, re.VERBOSE)
+    # Compiled regular expression for matching options with typical separators
+    OPTCRE = re.compile(_OPT_TMPL.format(delim="=|:"), re.VERBOSE)
+    # Compiled regular expression for matching options with optional values
+    # delimited using typical separators
+    OPTCRE_NV = re.compile(_OPT_NV_TMPL.format(delim="=|:"), re.VERBOSE)
+    # Compiled regular expression for matching leading whitespace in a line
+    NONSPACECRE = re.compile(r"\S")
+    # Possible boolean values in the configuration.
+    BOOLEAN_STATES = {
+        '1': True,
+        'yes': True,
+        'true': True,
+        'on': True,
+        '0': False,
+        'no': False,
+        'false': False,
+        'off': False,
+    }
+
+    def __init__(
+        self, defaults=None, dict_type=_default_dict, allow_no_value=False, **kwargs
+    ):
+
+        # keyword-only arguments
+        delimiters = kwargs.get('delimiters', ('=', ':'))
+        comment_prefixes = kwargs.get('comment_prefixes', ('#', ';'))
+        inline_comment_prefixes = kwargs.get('inline_comment_prefixes', None)
+        strict = kwargs.get('strict', True)
+        empty_lines_in_values = kwargs.get('empty_lines_in_values', True)
+        default_section = kwargs.get('default_section', DEFAULTSECT)
+        interpolation = kwargs.get('interpolation', _UNSET)
+        converters = kwargs.get('converters', _UNSET)
+
+        self._dict = dict_type
+        self._sections = self._dict()
+        self._defaults = self._dict()
+        self._converters = ConverterMapping(self)
+        self._proxies = self._dict()
+        self._proxies[default_section] = SectionProxy(self, default_section)
+        self._delimiters = tuple(delimiters)
+        if delimiters == ('=', ':'):
+            self._optcre = self.OPTCRE_NV if allow_no_value else self.OPTCRE
+        else:
+            d = "|".join(re.escape(d) for d in delimiters)
+            if allow_no_value:
+                self._optcre = re.compile(self._OPT_NV_TMPL.format(delim=d), re.VERBOSE)
+            else:
+                self._optcre = re.compile(self._OPT_TMPL.format(delim=d), re.VERBOSE)
+        self._comment_prefixes = tuple(comment_prefixes or ())
+        self._inline_comment_prefixes = tuple(inline_comment_prefixes or ())
+        self._strict = strict
+        self._allow_no_value = allow_no_value
+        self._empty_lines_in_values = empty_lines_in_values
+        self.default_section = default_section
+        self._interpolation = interpolation
+        if self._interpolation is _UNSET:
+            self._interpolation = self._DEFAULT_INTERPOLATION
+        if self._interpolation is None:
+            self._interpolation = Interpolation()
+        if converters is not _UNSET:
+            self._converters.update(converters)
+        if defaults:
+            self._read_defaults(defaults)
+
+    def defaults(self):
+        return self._defaults
+
+    def sections(self):
+        """Return a list of section names, excluding [DEFAULT]"""
+        # self._sections will never have [DEFAULT] in it
+        return list(self._sections.keys())
+
+    def add_section(self, section):
+        """Create a new section in the configuration.
+
+        Raise DuplicateSectionError if a section by the specified name
+        already exists. Raise ValueError if name is DEFAULT.
+        """
+        if section == self.default_section:
+            raise ValueError('Invalid section name: %r' % section)
+
+        if section in self._sections:
+            raise DuplicateSectionError(section)
+        self._sections[section] = self._dict()
+        self._proxies[section] = SectionProxy(self, section)
+
+    def has_section(self, section):
+        """Indicate whether the named section is present in the configuration.
+
+        The DEFAULT section is not acknowledged.
+        """
+        return section in self._sections
+
+    def options(self, section):
+        """Return a list of option names for the given section name."""
+        try:
+            opts = self._sections[section].copy()
+        except KeyError:
+            raise from_none(NoSectionError(section))
+        opts.update(self._defaults)
+        return list(opts.keys())
+
+    def read(self, filenames, encoding=None):
+        """Read and parse a filename or an iterable of filenames.
+
+        Files that cannot be opened are silently ignored; this is
+        designed so that you can specify an iterable of potential
+        configuration file locations (e.g. current directory, user's
+        home directory, systemwide directory), and all existing
+        configuration files in the iterable will be read.  A single
+        filename may also be given.
+
+        Return list of successfully read files.
+        """
+        if isinstance(filenames, (str, bytes, PathLike)):
+            filenames = [filenames]
+        read_ok = []
+        for filename in filenames:
+            if isinstance(filename, PathLike):
+                filename = fspath(filename)
+            try:
+                with open(filename, encoding=encoding) as fp:
+                    self._read(fp, filename)
+            except IOError:
+                continue
+            read_ok.append(filename)
+        return read_ok
+
+    def read_file(self, f, source=None):
+        """Like read() but the argument must be a file-like object.
+
+        The `f' argument must be iterable, returning one line at a time.
+        Optional second argument is the `source' specifying the name of the
+        file being read. If not given, it is taken from f.name. If `f' has no
+        `name' attribute, `<???>' is used.
+        """
+        if source is None:
+            try:
+                source = f.name
+            except AttributeError:
+                source = '<???>'
+        self._read(f, source)
+
+    def read_string(self, string, source='<string>'):
+        """Read configuration from a given string."""
+        sfile = io.StringIO(string)
+        self.read_file(sfile, source)
+
+    def read_dict(self, dictionary, source='<dict>'):
+        """Read configuration from a dictionary.
+
+        Keys are section names, values are dictionaries with keys and values
+        that should be present in the section. If the used dictionary type
+        preserves order, sections and their keys will be added in order.
+
+        All types held in the dictionary are converted to strings during
+        reading, including section names, option names and keys.
+
+        Optional second argument is the `source' specifying the name of the
+        dictionary being read.
+        """
+        elements_added = set()
+        for section, keys in dictionary.items():
+            section = str(section)
+            try:
+                self.add_section(section)
+            except (DuplicateSectionError, ValueError):
+                if self._strict and section in elements_added:
+                    raise
+            elements_added.add(section)
+            for key, value in keys.items():
+                key = self.optionxform(str(key))
+                if value is not None:
+                    value = str(value)
+                if self._strict and (section, key) in elements_added:
+                    raise DuplicateOptionError(section, key, source)
+                elements_added.add((section, key))
+                self.set(section, key, value)
+
+    def readfp(self, fp, filename=None):
+        """Deprecated, use read_file instead."""
+        warnings.warn(
+            "This method will be removed in future versions.  "
+            "Use 'parser.read_file()' instead.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        self.read_file(fp, source=filename)
+
+    def get(self, section, option, **kwargs):
+        """Get an option value for a given section.
+
+        If `vars' is provided, it must be a dictionary. The option is looked up
+        in `vars' (if provided), `section', and in `DEFAULTSECT' in that order.
+        If the key is not found and `fallback' is provided, it is used as
+        a fallback value. `None' can be provided as a `fallback' value.
+
+        If interpolation is enabled and the optional argument `raw' is False,
+        all interpolations are expanded in the return values.
+
+        Arguments `raw', `vars', and `fallback' are keyword only.
+
+        The section DEFAULT is special.
+        """
+        # keyword-only arguments
+        raw = kwargs.get('raw', False)
+        vars = kwargs.get('vars', None)
+        fallback = kwargs.get('fallback', _UNSET)
+
+        try:
+            d = self._unify_values(section, vars)
+        except NoSectionError:
+            if fallback is _UNSET:
+                raise
+            else:
+                return fallback
+        option = self.optionxform(option)
+        try:
+            value = d[option]
+        except KeyError:
+            if fallback is _UNSET:
+                raise NoOptionError(option, section)
+            else:
+                return fallback
+
+        if raw or value is None:
+            return value
+        else:
+            return self._interpolation.before_get(self, section, option, value, d)
+
+    def _get(self, section, conv, option, **kwargs):
+        return conv(self.get(section, option, **kwargs))
+
+    def _get_conv(self, section, option, conv, **kwargs):
+        # keyword-only arguments
+        kwargs.setdefault('raw', False)
+        kwargs.setdefault('vars', None)
+        fallback = kwargs.pop('fallback', _UNSET)
+        try:
+            return self._get(section, conv, option, **kwargs)
+        except (NoSectionError, NoOptionError):
+            if fallback is _UNSET:
+                raise
+            return fallback
+
+    # getint, getfloat and getboolean provided directly for backwards compat
+    def getint(self, section, option, **kwargs):
+        # keyword-only arguments
+        kwargs.setdefault('raw', False)
+        kwargs.setdefault('vars', None)
+        kwargs.setdefault('fallback', _UNSET)
+        return self._get_conv(section, option, int, **kwargs)
+
+    def getfloat(self, section, option, **kwargs):
+        # keyword-only arguments
+        kwargs.setdefault('raw', False)
+        kwargs.setdefault('vars', None)
+        kwargs.setdefault('fallback', _UNSET)
+        return self._get_conv(section, option, float, **kwargs)
+
+    def getboolean(self, section, option, **kwargs):
+        # keyword-only arguments
+        kwargs.setdefault('raw', False)
+        kwargs.setdefault('vars', None)
+        kwargs.setdefault('fallback', _UNSET)
+        return self._get_conv(section, option, self._convert_to_boolean, **kwargs)
+
+    def items(self, section=_UNSET, raw=False, vars=None):
+        """Return a list of (name, value) tuples for each option in a section.
+
+        All % interpolations are expanded in the return values, based on the
+        defaults passed into the constructor, unless the optional argument
+        `raw' is true.  Additional substitutions may be provided using the
+        `vars' argument, which must be a dictionary whose contents overrides
+        any pre-existing defaults.
+
+        The section DEFAULT is special.
+        """
+        if section is _UNSET:
+            return super(RawConfigParser, self).items()
+        d = self._defaults.copy()
+        try:
+            d.update(self._sections[section])
+        except KeyError:
+            if section != self.default_section:
+                raise NoSectionError(section)
+        orig_keys = list(d.keys())
+        # Update with the entry specific variables
+        if vars:
+            for key, value in vars.items():
+                d[self.optionxform(key)] = value
+        value_getter = lambda option: self._interpolation.before_get(
+            self, section, option, d[option], d
+        )
+        if raw:
+            value_getter = lambda option: d[option]
+        return [(option, value_getter(option)) for option in orig_keys]
+
+    def popitem(self):
+        """Remove a section from the parser and return it as
+        a (section_name, section_proxy) tuple. If no section is present, raise
+        KeyError.
+
+        The section DEFAULT is never returned because it cannot be removed.
+        """
+        for key in self.sections():
+            value = self[key]
+            del self[key]
+            return key, value
+        raise KeyError
+
+    def optionxform(self, optionstr):
+        return optionstr.lower()
+
+    def has_option(self, section, option):
+        """Check for the existence of a given option in a given section.
+        If the specified `section' is None or an empty string, DEFAULT is
+        assumed. If the specified `section' does not exist, returns False."""
+        if not section or section == self.default_section:
+            option = self.optionxform(option)
+            return option in self._defaults
+        elif section not in self._sections:
+            return False
+        else:
+            option = self.optionxform(option)
+            return option in self._sections[section] or option in self._defaults
+
+    def set(self, section, option, value=None):
+        """Set an option."""
+        if value:
+            value = self._interpolation.before_set(self, section, option, value)
+        if not section or section == self.default_section:
+            sectdict = self._defaults
+        else:
+            try:
+                sectdict = self._sections[section]
+            except KeyError:
+                raise from_none(NoSectionError(section))
+        sectdict[self.optionxform(option)] = value
+
+    def write(self, fp, space_around_delimiters=True):
+        """Write an .ini-format representation of the configuration state.
+
+        If `space_around_delimiters' is True (the default), delimiters
+        between keys and values are surrounded by spaces.
+        """
+        if space_around_delimiters:
+            d = " {0} ".format(self._delimiters[0])
+        else:
+            d = self._delimiters[0]
+        if self._defaults:
+            self._write_section(fp, self.default_section, self._defaults.items(), d)
+        for section in self._sections:
+            self._write_section(fp, section, self._sections[section].items(), d)
+
+    def _write_section(self, fp, section_name, section_items, delimiter):
+        """Write a single section to the specified `fp'."""
+        fp.write("[{0}]\n".format(section_name))
+        for key, value in section_items:
+            value = self._interpolation.before_write(self, section_name, key, value)
+            if value is not None or not self._allow_no_value:
+                value = delimiter + str(value).replace('\n', '\n\t')
+            else:
+                value = ""
+            fp.write("{0}{1}\n".format(key, value))
+        fp.write("\n")
+
+    def remove_option(self, section, option):
+        """Remove an option."""
+        if not section or section == self.default_section:
+            sectdict = self._defaults
+        else:
+            try:
+                sectdict = self._sections[section]
+            except KeyError:
+                raise from_none(NoSectionError(section))
+        option = self.optionxform(option)
+        existed = option in sectdict
+        if existed:
+            del sectdict[option]
+        return existed
+
+    def remove_section(self, section):
+        """Remove a file section."""
+        existed = section in self._sections
+        if existed:
+            del self._sections[section]
+            del self._proxies[section]
+        return existed
+
+    def __getitem__(self, key):
+        if key != self.default_section and not self.has_section(key):
+            raise KeyError(key)
+        return self._proxies[key]
+
+    def __setitem__(self, key, value):
+        # To conform with the mapping protocol, overwrites existing values in
+        # the section.
+        if key in self and self[key] is value:
+            return
+        # XXX this is not atomic if read_dict fails at any point. Then again,
+        # no update method in configparser is atomic in this implementation.
+        if key == self.default_section:
+            self._defaults.clear()
+        elif key in self._sections:
+            self._sections[key].clear()
+        self.read_dict({key: value})
+
+    def __delitem__(self, key):
+        if key == self.default_section:
+            raise ValueError("Cannot remove the default section.")
+        if not self.has_section(key):
+            raise KeyError(key)
+        self.remove_section(key)
+
+    def __contains__(self, key):
+        return key == self.default_section or self.has_section(key)
+
+    def __len__(self):
+        return len(self._sections) + 1  # the default section
+
+    def __iter__(self):
+        # XXX does it break when underlying container state changed?
+        return itertools.chain((self.default_section,), self._sections.keys())
+
+    def _read(self, fp, fpname):
+        """Parse a sectioned configuration file.
+
+        Each section in a configuration file contains a header, indicated by
+        a name in square brackets (`[]'), plus key/value options, indicated by
+        `name' and `value' delimited with a specific substring (`=' or `:' by
+        default).
+
+        Values can span multiple lines, as long as they are indented deeper
+        than the first line of the value. Depending on the parser's mode, blank
+        lines may be treated as parts of multiline values or ignored.
+
+        Configuration files may include comments, prefixed by specific
+        characters (`#' and `;' by default). Comments may appear on their own
+        in an otherwise empty line or may be entered in lines holding values or
+        section names.
+        """
+        elements_added = set()
+        cursect = None  # None, or a dictionary
+        sectname = None
+        optname = None
+        lineno = 0
+        indent_level = 0
+        e = None  # None, or an exception
+        for lineno, line in enumerate(fp, start=1):
+            comment_start = sys.maxsize
+            # strip inline comments
+            inline_prefixes = dict((p, -1) for p in self._inline_comment_prefixes)
+            while comment_start == sys.maxsize and inline_prefixes:
+                next_prefixes = {}
+                for prefix, index in inline_prefixes.items():
+                    index = line.find(prefix, index + 1)
+                    if index == -1:
+                        continue
+                    next_prefixes[prefix] = index
+                    if index == 0 or (index > 0 and line[index - 1].isspace()):
+                        comment_start = min(comment_start, index)
+                inline_prefixes = next_prefixes
+            # strip full line comments
+            for prefix in self._comment_prefixes:
+                if line.strip().startswith(prefix):
+                    comment_start = 0
+                    break
+            if comment_start == sys.maxsize:
+                comment_start = None
+            value = line[:comment_start].strip()
+            if not value:
+                if self._empty_lines_in_values:
+                    # add empty line to the value, but only if there was no
+                    # comment on the line
+                    if (
+                        comment_start is None
+                        and cursect is not None
+                        and optname
+                        and cursect[optname] is not None
+                    ):
+                        cursect[optname].append('')  # newlines added at join
+                else:
+                    # empty line marks end of value
+                    indent_level = sys.maxsize
+                continue
+            # continuation line?
+            first_nonspace = self.NONSPACECRE.search(line)
+            cur_indent_level = first_nonspace.start() if first_nonspace else 0
+            if cursect is not None and optname and cur_indent_level > indent_level:
+                cursect[optname].append(value)
+            # a section header or option header?
+            else:
+                indent_level = cur_indent_level
+                # is it a section header?
+                mo = self.SECTCRE.match(value)
+                if mo:
+                    sectname = mo.group('header')
+                    if sectname in self._sections:
+                        if self._strict and sectname in elements_added:
+                            raise DuplicateSectionError(sectname, fpname, lineno)
+                        cursect = self._sections[sectname]
+                        elements_added.add(sectname)
+                    elif sectname == self.default_section:
+                        cursect = self._defaults
+                    else:
+                        cursect = self._dict()
+                        self._sections[sectname] = cursect
+                        self._proxies[sectname] = SectionProxy(self, sectname)
+                        elements_added.add(sectname)
+                    # So sections can't start with a continuation line
+                    optname = None
+                # no section header in the file?
+                elif cursect is None:
+                    raise MissingSectionHeaderError(fpname, lineno, line)
+                # an option line?
+                else:
+                    mo = self._optcre.match(value)
+                    if mo:
+                        optname, vi, optval = mo.group('option', 'vi', 'value')
+                        if not optname:
+                            e = self._handle_error(e, fpname, lineno, line)
+                        optname = self.optionxform(optname.rstrip())
+                        if self._strict and (sectname, optname) in elements_added:
+                            raise DuplicateOptionError(
+                                sectname, optname, fpname, lineno
+                            )
+                        elements_added.add((sectname, optname))
+                        # This check is fine because the OPTCRE cannot
+                        # match if it would set optval to None
+                        if optval is not None:
+                            optval = optval.strip()
+                            cursect[optname] = [optval]
+                        else:
+                            # valueless option handling
+                            cursect[optname] = None
+                    else:
+                        # a non-fatal parsing error occurred. set up the
+                        # exception but keep going. the exception will be
+                        # raised at the end of the file and will contain a
+                        # list of all bogus lines
+                        e = self._handle_error(e, fpname, lineno, line)
+        self._join_multiline_values()
+        # if any parsing errors occurred, raise an exception
+        if e:
+            raise e
+
+    def _join_multiline_values(self):
+        defaults = self.default_section, self._defaults
+        all_sections = itertools.chain((defaults,), self._sections.items())
+        for section, options in all_sections:
+            for name, val in options.items():
+                if isinstance(val, list):
+                    val = '\n'.join(val).rstrip()
+                options[name] = self._interpolation.before_read(
+                    self, section, name, val
+                )
+
+    def _read_defaults(self, defaults):
+        """Read the defaults passed in the initializer.
+        Note: values can be non-string."""
+        for key, value in defaults.items():
+            self._defaults[self.optionxform(key)] = value
+
+    def _handle_error(self, exc, fpname, lineno, line):
+        if not exc:
+            exc = ParsingError(fpname)
+        exc.append(lineno, repr(line))
+        return exc
+
+    def _unify_values(self, section, vars):
+        """Create a sequence of lookups with 'vars' taking priority over
+        the 'section' which takes priority over the DEFAULTSECT.
+
+        """
+        sectiondict = {}
+        try:
+            sectiondict = self._sections[section]
+        except KeyError:
+            if section != self.default_section:
+                raise NoSectionError(section)
+        # Update with the entry specific variables
+        vardict = {}
+        if vars:
+            for key, value in vars.items():
+                if value is not None:
+                    value = str(value)
+                vardict[self.optionxform(key)] = value
+        return _ChainMap(vardict, sectiondict, self._defaults)
+
+    def _convert_to_boolean(self, value):
+        """Return a boolean value translating from other types if necessary.
+        """
+        if value.lower() not in self.BOOLEAN_STATES:
+            raise ValueError('Not a boolean: %s' % value)
+        return self.BOOLEAN_STATES[value.lower()]
+
+    def _validate_value_types(self, **kwargs):
+        """Raises a TypeError for non-string values.
+
+        The only legal non-string value if we allow valueless
+        options is None, so we need to check if the value is a
+        string if:
+        - we do not allow valueless options, or
+        - we allow valueless options but the value is not None
+
+        For compatibility reasons this method is not used in classic set()
+        for RawConfigParsers. It is invoked in every case for mapping protocol
+        access and in ConfigParser.set().
+        """
+        # keyword-only arguments
+        section = kwargs.get('section', "")
+        option = kwargs.get('option', "")
+        value = kwargs.get('value', "")
+
+        if PY2 and bytes in (type(section), type(option), type(value)):
+            # we allow for a little unholy magic for Python 2 so that
+            # people not using unicode_literals can still use the library
+            # conveniently
+            warnings.warn(
+                "You passed a bytestring. Implicitly decoding as UTF-8 string."
+                " This will not work on Python 3. Please switch to using"
+                " Unicode strings across the board.",
+                DeprecationWarning,
+                stacklevel=2,
+            )
+            if isinstance(section, bytes):
+                section = section.decode('utf8')
+            if isinstance(option, bytes):
+                option = option.decode('utf8')
+            if isinstance(value, bytes):
+                value = value.decode('utf8')
+
+        if not isinstance(section, str):
+            raise TypeError("section names must be strings")
+        if not isinstance(option, str):
+            raise TypeError("option keys must be strings")
+        if not self._allow_no_value or value:
+            if not isinstance(value, str):
+                raise TypeError("option values must be strings")
+
+        return section, option, value
+
+    @property
+    def converters(self):
+        return self._converters
+
+
+class ConfigParser(RawConfigParser):
+    """ConfigParser implementing interpolation."""
+
+    _DEFAULT_INTERPOLATION = BasicInterpolation()
+
+    def set(self, section, option, value=None):
+        """Set an option.  Extends RawConfigParser.set by validating type and
+        interpolation syntax on the value."""
+        _, option, value = self._validate_value_types(option=option, value=value)
+        super(ConfigParser, self).set(section, option, value)
+
+    def add_section(self, section):
+        """Create a new section in the configuration.  Extends
+        RawConfigParser.add_section by validating if the section name is
+        a string."""
+        section, _, _ = self._validate_value_types(section=section)
+        super(ConfigParser, self).add_section(section)
+
+    def _read_defaults(self, defaults):
+        """Reads the defaults passed in the initializer, implicitly converting
+        values to strings like the rest of the API.
+
+        Does not perform interpolation for backwards compatibility.
+        """
+        try:
+            hold_interpolation = self._interpolation
+            self._interpolation = Interpolation()
+            self.read_dict({self.default_section: defaults})
+        finally:
+            self._interpolation = hold_interpolation
+
+
+class SafeConfigParser(ConfigParser):
+    """ConfigParser alias for backwards compatibility purposes."""
+
+    def __init__(self, *args, **kwargs):
+        super(SafeConfigParser, self).__init__(*args, **kwargs)
+        warnings.warn(
+            "The SafeConfigParser class has been renamed to ConfigParser "
+            "in Python 3.2. This alias will be removed in future versions."
+            " Use ConfigParser directly instead.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+
+
+class SectionProxy(MutableMapping):
+    """A proxy for a single section from a parser."""
+
+    def __init__(self, parser, name):
+        """Creates a view on a section of the specified `name` in `parser`."""
+        self._parser = parser
+        self._name = name
+        for conv in parser.converters:
+            key = 'get' + conv
+            getter = functools.partial(self.get, _impl=getattr(parser, key))
+            setattr(self, key, getter)
+
+    def __repr__(self):
+        return '<Section: {0}>'.format(self._name)
+
+    def __getitem__(self, key):
+        if not self._parser.has_option(self._name, key):
+            raise KeyError(key)
+        return self._parser.get(self._name, key)
+
+    def __setitem__(self, key, value):
+        _, key, value = self._parser._validate_value_types(option=key, value=value)
+        return self._parser.set(self._name, key, value)
+
+    def __delitem__(self, key):
+        if not (
+            self._parser.has_option(self._name, key)
+            and self._parser.remove_option(self._name, key)
+        ):
+            raise KeyError(key)
+
+    def __contains__(self, key):
+        return self._parser.has_option(self._name, key)
+
+    def __len__(self):
+        return len(self._options())
+
+    def __iter__(self):
+        return self._options().__iter__()
+
+    def _options(self):
+        if self._name != self._parser.default_section:
+            return self._parser.options(self._name)
+        else:
+            return self._parser.defaults()
+
+    @property
+    def parser(self):
+        # The parser object of the proxy is read-only.
+        return self._parser
+
+    @property
+    def name(self):
+        # The name of the section on a proxy is read-only.
+        return self._name
+
+    def get(self, option, fallback=None, **kwargs):
+        """Get an option value.
+
+        Unless `fallback` is provided, `None` will be returned if the option
+        is not found.
+
+        """
+        # keyword-only arguments
+        kwargs.setdefault('raw', False)
+        kwargs.setdefault('vars', None)
+        _impl = kwargs.pop('_impl', None)
+        # If `_impl` is provided, it should be a getter method on the parser
+        # object that provides the desired type conversion.
+        if not _impl:
+            _impl = self._parser.get
+        return _impl(self._name, option, fallback=fallback, **kwargs)
+
+
+class ConverterMapping(MutableMapping):
+    """Enables reuse of get*() methods between the parser and section proxies.
+
+    If a parser class implements a getter directly, the value for the given
+    key will be ``None``. The presence of the converter name here enables
+    section proxies to find and use the implementation on the parser class.
+    """
+
+    GETTERCRE = re.compile(r"^get(?P<name>.+)$")
+
+    def __init__(self, parser):
+        self._parser = parser
+        self._data = {}
+        for getter in dir(self._parser):
+            m = self.GETTERCRE.match(getter)
+            if not m or not callable(getattr(self._parser, getter)):
+                continue
+            self._data[m.group('name')] = None  # See class docstring.
+
+    def __getitem__(self, key):
+        return self._data[key]
+
+    def __setitem__(self, key, value):
+        try:
+            k = 'get' + key
+        except TypeError:
+            raise ValueError(
+                'Incompatible key: {} (type: {})' ''.format(key, type(key))
+            )
+        if k == 'get':
+            raise ValueError('Incompatible key: cannot use "" as a name')
+        self._data[key] = value
+        func = functools.partial(self._parser._get_conv, conv=value)
+        func.converter = value
+        setattr(self._parser, k, func)
+        for proxy in self._parser.values():
+            getter = functools.partial(proxy.get, _impl=func)
+            setattr(proxy, k, getter)
+
+    def __delitem__(self, key):
+        try:
+            k = 'get' + (key or None)
+        except TypeError:
+            raise KeyError(key)
+        del self._data[key]
+        for inst in itertools.chain((self._parser,), self._parser.values()):
+            try:
+                delattr(inst, k)
+            except AttributeError:
+                # don't raise since the entry was present in _data, silently
+                # clean up
+                continue
+
+    def __iter__(self):
+        return iter(self._data)
+
+    def __len__(self):
+        return len(self._data)
diff --git a/contrib/deprecated/python/configparser/backports/configparser/helpers.py b/contrib/deprecated/python/configparser/backports/configparser/helpers.py
new file mode 100644
index 00000000000..e7eb72243f0
--- /dev/null
+++ b/contrib/deprecated/python/configparser/backports/configparser/helpers.py
@@ -0,0 +1,274 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+from __future__ import unicode_literals
+
+import abc
+import os
+
+try:
+    from collections.abc import MutableMapping
+except ImportError:
+    from collections import MutableMapping
+
+try:
+    from collections import UserDict
+except ImportError:
+    from UserDict import UserDict
+
+try:
+    from collections import OrderedDict
+except ImportError:
+    from ordereddict import OrderedDict
+
+try:
+    import pathlib
+except ImportError:
+    pathlib = None
+
+from io import open
+import sys
+
+try:
+    from thread import get_ident
+except ImportError:
+    try:
+        from _thread import get_ident
+    except ImportError:
+        from _dummy_thread import get_ident
+
+
+__all__ = ['UserDict', 'OrderedDict', 'open']
+
+
+PY2 = sys.version_info[0] == 2
+PY3 = sys.version_info[0] == 3
+
+native_str = str
+str = type('str')
+
+
+def from_none(exc):
+    """raise from_none(ValueError('a')) == raise ValueError('a') from None"""
+    exc.__cause__ = None
+    exc.__suppress_context__ = True
+    return exc
+
+
+# from reprlib 3.2.1
+def recursive_repr(fillvalue='...'):
+    'Decorator to make a repr function return fillvalue for a recursive call'
+
+    def decorating_function(user_function):
+        repr_running = set()
+
+        def wrapper(self):
+            key = id(self), get_ident()
+            if key in repr_running:
+                return fillvalue
+            repr_running.add(key)
+            try:
+                result = user_function(self)
+            finally:
+                repr_running.discard(key)
+            return result
+
+        # Can't use functools.wraps() here because of bootstrap issues
+        wrapper.__module__ = getattr(user_function, '__module__')
+        wrapper.__doc__ = getattr(user_function, '__doc__')
+        wrapper.__name__ = getattr(user_function, '__name__')
+        wrapper.__annotations__ = getattr(user_function, '__annotations__', {})
+        return wrapper
+
+    return decorating_function
+
+
+# from collections 3.2.1
+class _ChainMap(MutableMapping):
+    ''' A ChainMap groups multiple dicts (or other mappings) together
+    to create a single, updateable view.
+
+    The underlying mappings are stored in a list.  That list is public and can
+    accessed or updated using the *maps* attribute.  There is no other state.
+
+    Lookups search the underlying mappings successively until a key is found.
+    In contrast, writes, updates, and deletions only operate on the first
+    mapping.
+
+    '''
+
+    def __init__(self, *maps):
+        '''Initialize a ChainMap by setting *maps* to the given mappings.
+        If no mappings are provided, a single empty dictionary is used.
+
+        '''
+        self.maps = list(maps) or [{}]  # always at least one map
+
+    def __missing__(self, key):
+        raise KeyError(key)
+
+    def __getitem__(self, key):
+        for mapping in self.maps:
+            try:
+                # can't use 'key in mapping' with defaultdict
+                return mapping[key]
+            except KeyError:
+                pass
+        # support subclasses that define __missing__
+        return self.__missing__(key)
+
+    def get(self, key, default=None):
+        return self[key] if key in self else default
+
+    def __len__(self):
+        # reuses stored hash values if possible
+        return len(set().union(*self.maps))
+
+    def __iter__(self):
+        return iter(set().union(*self.maps))
+
+    def __contains__(self, key):
+        return any(key in m for m in self.maps)
+
+    @recursive_repr()
+    def __repr__(self):
+        return '{0.__class__.__name__}({1})'.format(
+            self, ', '.join(map(repr, self.maps))
+        )
+
+    @classmethod
+    def fromkeys(cls, iterable, *args):
+        'Create a ChainMap with a single dict created from the iterable.'
+        return cls(dict.fromkeys(iterable, *args))
+
+    def copy(self):
+        """
+        New ChainMap or subclass with a new copy of
+        maps[0] and refs to maps[1:]
+        """
+        return self.__class__(self.maps[0].copy(), *self.maps[1:])
+
+    __copy__ = copy
+
+    def new_child(self):  # like Django's Context.push()
+        'New ChainMap with a new dict followed by all previous maps.'
+        return self.__class__({}, *self.maps)
+
+    @property
+    def parents(self):  # like Django's Context.pop()
+        'New ChainMap from maps[1:].'
+        return self.__class__(*self.maps[1:])
+
+    def __setitem__(self, key, value):
+        self.maps[0][key] = value
+
+    def __delitem__(self, key):
+        try:
+            del self.maps[0][key]
+        except KeyError:
+            raise KeyError('Key not found in the first mapping: {!r}'.format(key))
+
+    def popitem(self):
+        """
+        Remove and return an item pair from maps[0].
+        Raise KeyError is maps[0] is empty.
+        """
+        try:
+            return self.maps[0].popitem()
+        except KeyError:
+            raise KeyError('No keys found in the first mapping.')
+
+    def pop(self, key, *args):
+        """
+        Remove *key* from maps[0] and return its value.
+        Raise KeyError if *key* not in maps[0].
+        """
+
+        try:
+            return self.maps[0].pop(key, *args)
+        except KeyError:
+            raise KeyError('Key not found in the first mapping: {!r}'.format(key))
+
+    def clear(self):
+        'Clear maps[0], leaving maps[1:] intact.'
+        self.maps[0].clear()
+
+
+try:
+    from collections import ChainMap
+except ImportError:
+    ChainMap = _ChainMap
+
+
+_ABC = getattr(
+    abc,
+    'ABC',
+    # Python 3.3 compatibility
+    abc.ABCMeta(native_str('__ABC'), (object,), dict(__metaclass__=abc.ABCMeta)),
+)
+
+
+class _PathLike(_ABC):
+
+    """Abstract base class for implementing the file system path protocol."""
+
+    @abc.abstractmethod
+    def __fspath__(self):
+        """Return the file system path representation of the object."""
+        raise NotImplementedError
+
+    @classmethod
+    def __subclasshook__(cls, subclass):
+        return bool(
+            hasattr(subclass, '__fspath__')
+            # workaround for Python 3.5
+            or pathlib
+            and issubclass(subclass, pathlib.Path)
+        )
+
+
+PathLike = getattr(os, 'PathLike', _PathLike)
+
+
+def _fspath(path):
+    """Return the path representation of a path-like object.
+
+    If str or bytes is passed in, it is returned unchanged. Otherwise the
+    os.PathLike interface is used to get the path representation. If the
+    path representation is not str or bytes, TypeError is raised. If the
+    provided path is not str, bytes, or os.PathLike, TypeError is raised.
+    """
+    if isinstance(path, (str, bytes)):
+        return path
+
+    if not hasattr(path, '__fspath__') and isinstance(path, pathlib.Path):
+        # workaround for Python 3.5
+        return str(path)
+
+    # Work from the object's type to match method resolution of other magic
+    # methods.
+    path_type = type(path)
+    try:
+        path_repr = path_type.__fspath__(path)
+    except AttributeError:
+
+        if hasattr(path_type, '__fspath__'):
+            raise
+        else:
+            raise TypeError(
+                "expected str, bytes or os.PathLike object, "
+                "not " + path_type.__name__
+            )
+    if isinstance(path_repr, (str, bytes)):
+        return path_repr
+    else:
+        raise TypeError(
+            "expected {}.__fspath__() to return str or bytes, "
+            "not {}".format(path_type.__name__, type(path_repr).__name__)
+        )
+
+
+fspath = getattr(os, 'fspath', _fspath)