add ydb deps

14 files changed, 1949 insertions, 0 deletions

diff --git a/contrib/python/contextlib2/py2/.dist-info/METADATA b/contrib/python/contextlib2/py2/.dist-info/METADATA
new file mode 100644
index 0000000000..c44f02deb5
--- /dev/null
+++ b/contrib/python/contextlib2/py2/.dist-info/METADATA
@@ -0,0 +1,70 @@
+Metadata-Version: 2.1
+Name: contextlib2
+Version: 0.6.0.post1
+Summary: Backports and enhancements for the contextlib module
+Home-page: http://contextlib2.readthedocs.org
+Author: Nick Coghlan
+Author-email: ncoghlan@gmail.com
+License: PSF License
+Platform: UNKNOWN
+Classifier: Development Status :: 5 - Production/Stable
+Classifier: License :: OSI Approved :: Python Software Foundation License
+Classifier: Programming Language :: Python :: 2
+Classifier: Programming Language :: Python :: 2.7
+Classifier: Programming Language :: Python :: 3
+Classifier: Programming Language :: Python :: 3.4
+Classifier: Programming Language :: Python :: 3.5
+Classifier: Programming Language :: Python :: 3.6
+Classifier: Programming Language :: Python :: 3.7
+Requires-Python: >=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*
+
+.. image:: https://jazzband.co/static/img/badge.svg
+   :target: https://jazzband.co/
+   :alt: Jazzband
+
+.. image:: https://readthedocs.org/projects/contextlib2/badge/?version=latest
+   :target: https://contextlib2.readthedocs.org/
+   :alt: Latest Docs
+
+.. image:: https://img.shields.io/travis/jazzband/contextlib2/master.svg
+   :target: http://travis-ci.org/jazzband/contextlib2
+
+.. image:: https://coveralls.io/repos/github/jazzband/contextlib2/badge.svg?branch=master
+   :target: https://coveralls.io/github/jazzband/contextlib2?branch=master
+
+.. image:: https://landscape.io/github/jazzband/contextlib2/master/landscape.svg
+   :target: https://landscape.io/github/jazzband/contextlib2/
+
+contextlib2 is a backport of the `standard library's contextlib
+module <https://docs.python.org/3.5/library/contextlib.html>`_ to
+earlier Python versions.
+
+It also serves as a real world proving ground for possible future
+enhancements to the standard library version.
+
+Development
+-----------
+
+contextlib2 has no runtime dependencies, but requires ``unittest2`` for testing
+on Python 2.x, as well as ``setuptools`` and ``wheel`` to generate universal
+wheel archives.
+
+Local testing is just a matter of running ``python test_contextlib2.py``.
+
+You can test against multiple versions of Python with
+`tox <https://tox.testrun.org/>`_::
+
+    pip install tox
+    tox
+
+Versions currently tested in both tox and Travis CI are:
+
+* CPython 2.7
+* CPython 3.4
+* CPython 3.5
+* CPython 3.6
+* CPython 3.7
+* PyPy
+* PyPy3
+
+
diff --git a/contrib/python/contextlib2/py2/.dist-info/top_level.txt b/contrib/python/contextlib2/py2/.dist-info/top_level.txt
new file mode 100644
index 0000000000..03fdf8ed24
--- /dev/null
+++ b/contrib/python/contextlib2/py2/.dist-info/top_level.txt
@@ -0,0 +1 @@
+contextlib2
diff --git a/contrib/python/contextlib2/py2/LICENSE.txt b/contrib/python/contextlib2/py2/LICENSE.txt
new file mode 100644
index 0000000000..5de20277df
--- /dev/null
+++ b/contrib/python/contextlib2/py2/LICENSE.txt
@@ -0,0 +1,122 @@
+
+
+A. HISTORY OF THE SOFTWARE
+==========================
+
+contextlib2 is a derivative of the contextlib module distributed by the PSF
+as part of the Python standard library. According, it is itself redistributed
+under the PSF license (reproduced in full below). As the contextlib module
+was added only in Python 2.5, the licenses for earlier Python versions are
+not applicable and have not been included.
+
+Python was created in the early 1990s by Guido van Rossum at Stichting
+Mathematisch Centrum (CWI, see http://www.cwi.nl) in the Netherlands
+as a successor of a language called ABC.  Guido remains Python's
+principal author, although it includes many contributions from others.
+
+In 1995, Guido continued his work on Python at the Corporation for
+National Research Initiatives (CNRI, see http://www.cnri.reston.va.us)
+in Reston, Virginia where he released several versions of the
+software.
+
+In May 2000, Guido and the Python core development team moved to
+BeOpen.com to form the BeOpen PythonLabs team.  In October of the same
+year, the PythonLabs team moved to Digital Creations (now Zope
+Corporation, see http://www.zope.com).  In 2001, the Python Software
+Foundation (PSF, see http://www.python.org/psf/) was formed, a
+non-profit organization created specifically to own Python-related
+Intellectual Property.  Zope Corporation is a sponsoring member of
+the PSF.
+
+All Python releases are Open Source (see http://www.opensource.org for
+the Open Source Definition).  Historically, most, but not all, Python
+releases have also been GPL-compatible; the table below summarizes
+the various releases that included the contextlib module.
+
+    Release         Derived     Year        Owner       GPL-
+                    from                                compatible? (1)
+
+    2.5             2.4         2006        PSF         yes
+    2.5.1           2.5         2007        PSF         yes
+    2.5.2           2.5.1       2008        PSF         yes
+    2.5.3           2.5.2       2008        PSF         yes
+    2.6             2.5         2008        PSF         yes
+    2.6.1           2.6         2008        PSF         yes
+    2.6.2           2.6.1       2009        PSF         yes
+    2.6.3           2.6.2       2009        PSF         yes
+    2.6.4           2.6.3       2009        PSF         yes
+    2.6.5           2.6.4       2010        PSF         yes
+    3.0             2.6         2008        PSF         yes
+    3.0.1           3.0         2009        PSF         yes
+    3.1             3.0.1       2009        PSF         yes
+    3.1.1           3.1         2009        PSF         yes
+    3.1.2           3.1.1       2010        PSF         yes
+    3.1.3           3.1.2       2010        PSF         yes
+    3.1.4           3.1.3       2011        PSF         yes
+    3.2             3.1         2011        PSF         yes
+    3.2.1           3.2         2011        PSF         yes
+    3.2.2           3.2.1       2011        PSF         yes
+    3.3             3.2         2012        PSF         yes
+
+Footnotes:
+
+(1) GPL-compatible doesn't mean that we're distributing Python under
+    the GPL.  All Python licenses, unlike the GPL, let you distribute
+    a modified version without making your changes open source.  The
+    GPL-compatible licenses make it possible to combine Python with
+    other software that is released under the GPL; the others don't.
+
+Thanks to the many outside volunteers who have worked under Guido's
+direction to make these releases possible.
+
+
+B. TERMS AND CONDITIONS FOR ACCESSING OR OTHERWISE USING PYTHON
+===============================================================
+
+PYTHON SOFTWARE FOUNDATION LICENSE VERSION 2
+--------------------------------------------
+
+1. This LICENSE AGREEMENT is between the Python Software Foundation
+("PSF"), and the Individual or Organization ("Licensee") accessing and
+otherwise using this software ("Python") in source or binary form and
+its associated documentation.
+
+2. Subject to the terms and conditions of this License Agreement, PSF hereby
+grants Licensee a nonexclusive, royalty-free, world-wide license to reproduce,
+analyze, test, perform and/or display publicly, prepare derivative works,
+distribute, and otherwise use Python alone or in any derivative version,
+provided, however, that PSF's License Agreement and PSF's notice of copyright,
+i.e., "Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
+2011 Python Software Foundation; All Rights Reserved" are retained in Python
+alone or in any derivative version prepared by Licensee.
+
+3. In the event Licensee prepares a derivative work that is based on
+or incorporates Python or any part thereof, and wants to make
+the derivative work available to others as provided herein, then
+Licensee hereby agrees to include in any such work a brief summary of
+the changes made to Python.
+
+4. PSF is making Python available to Licensee on an "AS IS"
+basis.  PSF MAKES NO REPRESENTATIONS OR WARRANTIES, EXPRESS OR
+IMPLIED.  BY WAY OF EXAMPLE, BUT NOT LIMITATION, PSF MAKES NO AND
+DISCLAIMS ANY REPRESENTATION OR WARRANTY OF MERCHANTABILITY OR FITNESS
+FOR ANY PARTICULAR PURPOSE OR THAT THE USE OF PYTHON WILL NOT
+INFRINGE ANY THIRD PARTY RIGHTS.
+
+5. PSF SHALL NOT BE LIABLE TO LICENSEE OR ANY OTHER USERS OF PYTHON
+FOR ANY INCIDENTAL, SPECIAL, OR CONSEQUENTIAL DAMAGES OR LOSS AS
+A RESULT OF MODIFYING, DISTRIBUTING, OR OTHERWISE USING PYTHON,
+OR ANY DERIVATIVE THEREOF, EVEN IF ADVISED OF THE POSSIBILITY THEREOF.
+
+6. This License Agreement will automatically terminate upon a material
+breach of its terms and conditions.
+
+7. Nothing in this License Agreement shall be deemed to create any
+relationship of agency, partnership, or joint venture between PSF and
+Licensee.  This License Agreement does not grant permission to use PSF
+trademarks or trade name in a trademark sense to endorse or promote
+products or services of Licensee, or any third party.
+
+8. By copying, installing or otherwise using Python, Licensee
+agrees to be bound by the terms and conditions of this License
+Agreement.
diff --git a/contrib/python/contextlib2/py2/README.rst b/contrib/python/contextlib2/py2/README.rst
new file mode 100644
index 0000000000..7fe170f1ff
--- /dev/null
+++ b/contrib/python/contextlib2/py2/README.rst
@@ -0,0 +1,48 @@
+.. image:: https://jazzband.co/static/img/badge.svg
+   :target: https://jazzband.co/
+   :alt: Jazzband
+
+.. image:: https://readthedocs.org/projects/contextlib2/badge/?version=latest
+   :target: https://contextlib2.readthedocs.org/
+   :alt: Latest Docs
+
+.. image:: https://img.shields.io/travis/jazzband/contextlib2/master.svg
+   :target: http://travis-ci.org/jazzband/contextlib2
+
+.. image:: https://coveralls.io/repos/github/jazzband/contextlib2/badge.svg?branch=master
+   :target: https://coveralls.io/github/jazzband/contextlib2?branch=master
+
+.. image:: https://landscape.io/github/jazzband/contextlib2/master/landscape.svg
+   :target: https://landscape.io/github/jazzband/contextlib2/
+
+contextlib2 is a backport of the `standard library's contextlib
+module <https://docs.python.org/3.5/library/contextlib.html>`_ to
+earlier Python versions.
+
+It also serves as a real world proving ground for possible future
+enhancements to the standard library version.
+
+Development
+-----------
+
+contextlib2 has no runtime dependencies, but requires ``unittest2`` for testing
+on Python 2.x, as well as ``setuptools`` and ``wheel`` to generate universal
+wheel archives.
+
+Local testing is just a matter of running ``python test_contextlib2.py``.
+
+You can test against multiple versions of Python with
+`tox <https://tox.testrun.org/>`_::
+
+    pip install tox
+    tox
+
+Versions currently tested in both tox and Travis CI are:
+
+* CPython 2.7
+* CPython 3.4
+* CPython 3.5
+* CPython 3.6
+* CPython 3.7
+* PyPy
+* PyPy3
diff --git a/contrib/python/contextlib2/py2/contextlib2.py b/contrib/python/contextlib2/py2/contextlib2.py
new file mode 100644
index 0000000000..3aae8f4117
--- /dev/null
+++ b/contrib/python/contextlib2/py2/contextlib2.py
@@ -0,0 +1,518 @@
+"""contextlib2 - backports and enhancements to the contextlib module"""
+
+import abc
+import sys
+import warnings
+from collections import deque
+from functools import wraps
+
+__all__ = ["contextmanager", "closing", "nullcontext",
+           "AbstractContextManager",
+           "ContextDecorator", "ExitStack",
+           "redirect_stdout", "redirect_stderr", "suppress"]
+
+# Backwards compatibility
+__all__ += ["ContextStack"]
+
+
+# Backport abc.ABC
+if sys.version_info[:2] >= (3, 4):
+    _abc_ABC = abc.ABC
+else:
+    _abc_ABC = abc.ABCMeta('ABC', (object,), {'__slots__': ()})
+
+
+# Backport classic class MRO
+def _classic_mro(C, result):
+    if C in result:
+        return
+    result.append(C)
+    for B in C.__bases__:
+        _classic_mro(B, result)
+    return result
+
+
+# Backport _collections_abc._check_methods
+def _check_methods(C, *methods):
+    try:
+        mro = C.__mro__
+    except AttributeError:
+        mro = tuple(_classic_mro(C, []))
+
+    for method in methods:
+        for B in mro:
+            if method in B.__dict__:
+                if B.__dict__[method] is None:
+                    return NotImplemented
+                break
+        else:
+            return NotImplemented
+    return True
+
+
+class AbstractContextManager(_abc_ABC):
+    """An abstract base class for context managers."""
+
+    def __enter__(self):
+        """Return `self` upon entering the runtime context."""
+        return self
+
+    @abc.abstractmethod
+    def __exit__(self, exc_type, exc_value, traceback):
+        """Raise any exception triggered within the runtime context."""
+        return None
+
+    @classmethod
+    def __subclasshook__(cls, C):
+        """Check whether subclass is considered a subclass of this ABC."""
+        if cls is AbstractContextManager:
+            return _check_methods(C, "__enter__", "__exit__")
+        return NotImplemented
+
+
+class ContextDecorator(object):
+    """A base class or mixin that enables context managers to work as decorators."""
+
+    def refresh_cm(self):
+        """Returns the context manager used to actually wrap the call to the
+        decorated function.
+
+        The default implementation just returns *self*.
+
+        Overriding this method allows otherwise one-shot context managers
+        like _GeneratorContextManager to support use as decorators via
+        implicit recreation.
+
+        DEPRECATED: refresh_cm was never added to the standard library's
+                    ContextDecorator API
+        """
+        warnings.warn("refresh_cm was never added to the standard library",
+                      DeprecationWarning)
+        return self._recreate_cm()
+
+    def _recreate_cm(self):
+        """Return a recreated instance of self.
+
+        Allows an otherwise one-shot context manager like
+        _GeneratorContextManager to support use as
+        a decorator via implicit recreation.
+
+        This is a private interface just for _GeneratorContextManager.
+        See issue #11647 for details.
+        """
+        return self
+
+    def __call__(self, func):
+        @wraps(func)
+        def inner(*args, **kwds):
+            with self._recreate_cm():
+                return func(*args, **kwds)
+        return inner
+
+
+class _GeneratorContextManager(ContextDecorator):
+    """Helper for @contextmanager decorator."""
+
+    def __init__(self, func, args, kwds):
+        self.gen = func(*args, **kwds)
+        self.func, self.args, self.kwds = func, args, kwds
+        # Issue 19330: ensure context manager instances have good docstrings
+        doc = getattr(func, "__doc__", None)
+        if doc is None:
+            doc = type(self).__doc__
+        self.__doc__ = doc
+        # Unfortunately, this still doesn't provide good help output when
+        # inspecting the created context manager instances, since pydoc
+        # currently bypasses the instance docstring and shows the docstring
+        # for the class instead.
+        # See http://bugs.python.org/issue19404 for more details.
+
+    def _recreate_cm(self):
+        # _GCM instances are one-shot context managers, so the
+        # CM must be recreated each time a decorated function is
+        # called
+        return self.__class__(self.func, self.args, self.kwds)
+
+    def __enter__(self):
+        try:
+            return next(self.gen)
+        except StopIteration:
+            raise RuntimeError("generator didn't yield")
+
+    def __exit__(self, type, value, traceback):
+        if type is None:
+            try:
+                next(self.gen)
+            except StopIteration:
+                return
+            else:
+                raise RuntimeError("generator didn't stop")
+        else:
+            if value is None:
+                # Need to force instantiation so we can reliably
+                # tell if we get the same exception back
+                value = type()
+            try:
+                self.gen.throw(type, value, traceback)
+                raise RuntimeError("generator didn't stop after throw()")
+            except StopIteration as exc:
+                # Suppress StopIteration *unless* it's the same exception that
+                # was passed to throw().  This prevents a StopIteration
+                # raised inside the "with" statement from being suppressed.
+                return exc is not value
+            except RuntimeError as exc:
+                # Don't re-raise the passed in exception
+                if exc is value:
+                    return False
+                # Likewise, avoid suppressing if a StopIteration exception
+                # was passed to throw() and later wrapped into a RuntimeError
+                # (see PEP 479).
+                if _HAVE_EXCEPTION_CHAINING and exc.__cause__ is value:
+                    return False
+                raise
+            except:
+                # only re-raise if it's *not* the exception that was
+                # passed to throw(), because __exit__() must not raise
+                # an exception unless __exit__() itself failed.  But throw()
+                # has to raise the exception to signal propagation, so this
+                # fixes the impedance mismatch between the throw() protocol
+                # and the __exit__() protocol.
+                #
+                if sys.exc_info()[1] is not value:
+                    raise
+
+
+def contextmanager(func):
+    """@contextmanager decorator.
+
+    Typical usage:
+
+        @contextmanager
+        def some_generator(<arguments>):
+            <setup>
+            try:
+                yield <value>
+            finally:
+                <cleanup>
+
+    This makes this:
+
+        with some_generator(<arguments>) as <variable>:
+            <body>
+
+    equivalent to this:
+
+        <setup>
+        try:
+            <variable> = <value>
+            <body>
+        finally:
+            <cleanup>
+
+    """
+    @wraps(func)
+    def helper(*args, **kwds):
+        return _GeneratorContextManager(func, args, kwds)
+    return helper
+
+
+class closing(object):
+    """Context to automatically close something at the end of a block.
+
+    Code like this:
+
+        with closing(<module>.open(<arguments>)) as f:
+            <block>
+
+    is equivalent to this:
+
+        f = <module>.open(<arguments>)
+        try:
+            <block>
+        finally:
+            f.close()
+
+    """
+    def __init__(self, thing):
+        self.thing = thing
+
+    def __enter__(self):
+        return self.thing
+
+    def __exit__(self, *exc_info):
+        self.thing.close()
+
+
+class _RedirectStream(object):
+
+    _stream = None
+
+    def __init__(self, new_target):
+        self._new_target = new_target
+        # We use a list of old targets to make this CM re-entrant
+        self._old_targets = []
+
+    def __enter__(self):
+        self._old_targets.append(getattr(sys, self._stream))
+        setattr(sys, self._stream, self._new_target)
+        return self._new_target
+
+    def __exit__(self, exctype, excinst, exctb):
+        setattr(sys, self._stream, self._old_targets.pop())
+
+
+class redirect_stdout(_RedirectStream):
+    """Context manager for temporarily redirecting stdout to another file.
+
+        # How to send help() to stderr
+        with redirect_stdout(sys.stderr):
+            help(dir)
+
+        # How to write help() to a file
+        with open('help.txt', 'w') as f:
+            with redirect_stdout(f):
+                help(pow)
+    """
+
+    _stream = "stdout"
+
+
+class redirect_stderr(_RedirectStream):
+    """Context manager for temporarily redirecting stderr to another file."""
+
+    _stream = "stderr"
+
+
+class suppress(object):
+    """Context manager to suppress specified exceptions
+
+    After the exception is suppressed, execution proceeds with the next
+    statement following the with statement.
+
+         with suppress(FileNotFoundError):
+             os.remove(somefile)
+         # Execution still resumes here if the file was already removed
+    """
+
+    def __init__(self, *exceptions):
+        self._exceptions = exceptions
+
+    def __enter__(self):
+        pass
+
+    def __exit__(self, exctype, excinst, exctb):
+        # Unlike isinstance and issubclass, CPython exception handling
+        # currently only looks at the concrete type hierarchy (ignoring
+        # the instance and subclass checking hooks). While Guido considers
+        # that a bug rather than a feature, it's a fairly hard one to fix
+        # due to various internal implementation details. suppress provides
+        # the simpler issubclass based semantics, rather than trying to
+        # exactly reproduce the limitations of the CPython interpreter.
+        #
+        # See http://bugs.python.org/issue12029 for more details
+        return exctype is not None and issubclass(exctype, self._exceptions)
+
+
+# Context manipulation is Python 3 only
+_HAVE_EXCEPTION_CHAINING = sys.version_info[0] >= 3
+if _HAVE_EXCEPTION_CHAINING:
+    def _make_context_fixer(frame_exc):
+        def _fix_exception_context(new_exc, old_exc):
+            # Context may not be correct, so find the end of the chain
+            while 1:
+                exc_context = new_exc.__context__
+                if exc_context is old_exc:
+                    # Context is already set correctly (see issue 20317)
+                    return
+                if exc_context is None or exc_context is frame_exc:
+                    break
+                new_exc = exc_context
+            # Change the end of the chain to point to the exception
+            # we expect it to reference
+            new_exc.__context__ = old_exc
+        return _fix_exception_context
+
+    def _reraise_with_existing_context(exc_details):
+        try:
+            # bare "raise exc_details[1]" replaces our carefully
+            # set-up context
+            fixed_ctx = exc_details[1].__context__
+            raise exc_details[1]
+        except BaseException:
+            exc_details[1].__context__ = fixed_ctx
+            raise
+else:
+    # No exception context in Python 2
+    def _make_context_fixer(frame_exc):
+        return lambda new_exc, old_exc: None
+
+    # Use 3 argument raise in Python 2,
+    # but use exec to avoid SyntaxError in Python 3
+    def _reraise_with_existing_context(exc_details):
+        exc_type, exc_value, exc_tb = exc_details
+        exec("raise exc_type, exc_value, exc_tb")
+
+# Handle old-style classes if they exist
+try:
+    from types import InstanceType
+except ImportError:
+    # Python 3 doesn't have old-style classes
+    _get_type = type
+else:
+    # Need to handle old-style context managers on Python 2
+    def _get_type(obj):
+        obj_type = type(obj)
+        if obj_type is InstanceType:
+            return obj.__class__  # Old-style class
+        return obj_type  # New-style class
+
+
+# Inspired by discussions on http://bugs.python.org/issue13585
+class ExitStack(object):
+    """Context manager for dynamic management of a stack of exit callbacks
+
+    For example:
+
+        with ExitStack() as stack:
+            files = [stack.enter_context(open(fname)) for fname in filenames]
+            # All opened files will automatically be closed at the end of
+            # the with statement, even if attempts to open files later
+            # in the list raise an exception
+
+    """
+    def __init__(self):
+        self._exit_callbacks = deque()
+
+    def pop_all(self):
+        """Preserve the context stack by transferring it to a new instance"""
+        new_stack = type(self)()
+        new_stack._exit_callbacks = self._exit_callbacks
+        self._exit_callbacks = deque()
+        return new_stack
+
+    def _push_cm_exit(self, cm, cm_exit):
+        """Helper to correctly register callbacks to __exit__ methods"""
+        def _exit_wrapper(*exc_details):
+            return cm_exit(cm, *exc_details)
+        _exit_wrapper.__self__ = cm
+        self.push(_exit_wrapper)
+
+    def push(self, exit):
+        """Registers a callback with the standard __exit__ method signature
+
+        Can suppress exceptions the same way __exit__ methods can.
+
+        Also accepts any object with an __exit__ method (registering a call
+        to the method instead of the object itself)
+        """
+        # We use an unbound method rather than a bound method to follow
+        # the standard lookup behaviour for special methods
+        _cb_type = _get_type(exit)
+        try:
+            exit_method = _cb_type.__exit__
+        except AttributeError:
+            # Not a context manager, so assume its a callable
+            self._exit_callbacks.append(exit)
+        else:
+            self._push_cm_exit(exit, exit_method)
+        return exit # Allow use as a decorator
+
+    def callback(self, callback, *args, **kwds):
+        """Registers an arbitrary callback and arguments.
+
+        Cannot suppress exceptions.
+        """
+        def _exit_wrapper(exc_type, exc, tb):
+            callback(*args, **kwds)
+        # We changed the signature, so using @wraps is not appropriate, but
+        # setting __wrapped__ may still help with introspection
+        _exit_wrapper.__wrapped__ = callback
+        self.push(_exit_wrapper)
+        return callback # Allow use as a decorator
+
+    def enter_context(self, cm):
+        """Enters the supplied context manager
+
+        If successful, also pushes its __exit__ method as a callback and
+        returns the result of the __enter__ method.
+        """
+        # We look up the special methods on the type to match the with statement
+        _cm_type = _get_type(cm)
+        _exit = _cm_type.__exit__
+        result = _cm_type.__enter__(cm)
+        self._push_cm_exit(cm, _exit)
+        return result
+
+    def close(self):
+        """Immediately unwind the context stack"""
+        self.__exit__(None, None, None)
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *exc_details):
+        received_exc = exc_details[0] is not None
+
+        # We manipulate the exception state so it behaves as though
+        # we were actually nesting multiple with statements
+        frame_exc = sys.exc_info()[1]
+        _fix_exception_context = _make_context_fixer(frame_exc)
+
+        # Callbacks are invoked in LIFO order to match the behaviour of
+        # nested context managers
+        suppressed_exc = False
+        pending_raise = False
+        while self._exit_callbacks:
+            cb = self._exit_callbacks.pop()
+            try:
+                if cb(*exc_details):
+                    suppressed_exc = True
+                    pending_raise = False
+                    exc_details = (None, None, None)
+            except:
+                new_exc_details = sys.exc_info()
+                # simulate the stack of exceptions by setting the context
+                _fix_exception_context(new_exc_details[1], exc_details[1])
+                pending_raise = True
+                exc_details = new_exc_details
+        if pending_raise:
+            _reraise_with_existing_context(exc_details)
+        return received_exc and suppressed_exc
+
+
+# Preserve backwards compatibility
+class ContextStack(ExitStack):
+    """Backwards compatibility alias for ExitStack"""
+
+    def __init__(self):
+        warnings.warn("ContextStack has been renamed to ExitStack",
+                      DeprecationWarning)
+        super(ContextStack, self).__init__()
+
+    def register_exit(self, callback):
+        return self.push(callback)
+
+    def register(self, callback, *args, **kwds):
+        return self.callback(callback, *args, **kwds)
+
+    def preserve(self):
+        return self.pop_all()
+
+
+class nullcontext(AbstractContextManager):
+    """Context manager that does no additional processing.
+    Used as a stand-in for a normal context manager, when a particular
+    block of code is only sometimes used with a normal context manager:
+    cm = optional_cm if condition else nullcontext()
+    with cm:
+        # Perform operation, using optional_cm if condition is True
+    """
+
+    def __init__(self, enter_result=None):
+        self.enter_result = enter_result
+
+    def __enter__(self):
+        return self.enter_result
+
+    def __exit__(self, *excinfo):
+        pass
diff --git a/contrib/python/contextlib2/py2/ya.make b/contrib/python/contextlib2/py2/ya.make
new file mode 100644
index 0000000000..34e15ca73e
--- /dev/null
+++ b/contrib/python/contextlib2/py2/ya.make
@@ -0,0 +1,22 @@
+# Generated by devtools/yamaker (pypi).
+
+PY2_LIBRARY()
+
+VERSION(0.6.0.post1)
+
+LICENSE(PSF-2.0)
+
+NO_LINT()
+
+PY_SRCS(
+    TOP_LEVEL
+    contextlib2.py
+)
+
+RESOURCE_FILES(
+    PREFIX contrib/python/contextlib2/py2/
+    .dist-info/METADATA
+    .dist-info/top_level.txt
+)
+
+END()
diff --git a/contrib/python/contextlib2/py3/.dist-info/METADATA b/contrib/python/contextlib2/py3/.dist-info/METADATA
new file mode 100644
index 0000000000..b2427d0476
--- /dev/null
+++ b/contrib/python/contextlib2/py3/.dist-info/METADATA
@@ -0,0 +1,113 @@
+Metadata-Version: 2.1
+Name: contextlib2
+Version: 21.6.0
+Summary: Backports and enhancements for the contextlib module
+Home-page: http://contextlib2.readthedocs.org
+Author: Nick Coghlan
+Author-email: ncoghlan@gmail.com
+License: PSF License
+Platform: UNKNOWN
+Classifier: Development Status :: 5 - Production/Stable
+Classifier: License :: OSI Approved :: Apache Software License
+Classifier: License :: OSI Approved :: Python Software Foundation License
+Classifier: Programming Language :: Python :: 3
+Classifier: Programming Language :: Python :: 3.6
+Classifier: Programming Language :: Python :: 3.7
+Classifier: Programming Language :: Python :: 3.8
+Classifier: Programming Language :: Python :: 3.9
+Classifier: Programming Language :: Python :: 3.10
+Requires-Python: >=3.6
+License-File: LICENSE.txt
+
+.. image:: https://jazzband.co/static/img/badge.svg
+   :target: https://jazzband.co/
+   :alt: Jazzband
+
+.. image:: https://github.com/jazzband/contextlib2/workflows/Test/badge.svg
+   :target: https://github.com/jazzband/contextlib2/actions
+   :alt: Tests
+
+.. image:: https://codecov.io/gh/jazzband/contextlib2/branch/master/graph/badge.svg
+   :target: https://codecov.io/gh/jazzband/contextlib2
+   :alt: Coverage
+
+.. image:: https://readthedocs.org/projects/contextlib2/badge/?version=latest
+   :target: https://contextlib2.readthedocs.org/
+   :alt: Latest Docs
+
+contextlib2 is a backport of the `standard library's contextlib
+module <https://docs.python.org/3/library/contextlib.html>`_ to
+earlier Python versions.
+
+It also sometimes serves as a real world proving ground for possible future
+enhancements to the standard library version.
+
+Licensing
+---------
+
+As a backport of Python standard library software, the implementation, test
+suite and other supporting files for this project are distributed under the
+Python Software License used for the CPython reference implementation.
+
+The one exception is the included type hints file, which comes from the
+``typeshed`` project, and is hence distributed under the Apache License 2.0.
+
+Development
+-----------
+
+contextlib2 has no runtime dependencies, but requires ``setuptools`` and
+``wheel`` at build time to generate universal wheel archives.
+
+Local testing is a matter of running::
+
+    python3 -m unittest discover -t . -s test
+
+You can test against multiple versions of Python with
+`tox <https://tox.testrun.org/>`_::
+
+    pip install tox
+    tox
+
+Versions currently tested in both tox and GitHub Actions are:
+
+* CPython 3.6
+* CPython 3.7
+* CPython 3.8
+* CPython 3.9
+* CPython 3.10
+* PyPy3
+
+Updating to a new stdlib reference version
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+As of Python 3.10, 4 files needed to be copied from the CPython reference
+implementation to contextlib2:
+
+* ``Doc/contextlib.rst`` -> ``docs/contextlib2.rst``
+* ``Lib/contextlib.py`` -> ``contextlib2/__init__.py``
+* ``Lib/test/test_contextlib.py`` -> ``test/test_contextlib.py``
+* ``Lib/test/test_contextlib_async.py`` -> ``test/test_contextlib_async.py``
+
+The corresponding version of ``contextlib2/__init__.pyi`` also needs to be
+retrieved from the ``typeshed`` project::
+
+    wget https://raw.githubusercontent.com/python/typeshed/master/stdlib/contextlib.pyi
+
+For the 3.10 sync, the only changes needed to the test files were to import from
+``contextlib2`` rather than ``contextlib``. The test directory is laid out so
+that the test suite's imports from ``test.support`` work the same way they do in
+the main CPython test suite.
+
+The following patch files are saved in the ``dev`` directory:
+
+* changes made to ``contextlib2/__init__.py`` to get it to run on the older
+  versions (and to add back in the deprecated APIs that never graduated to
+  the standard library version)
+* changes made to ``contextlib2/__init__.pyi`` to make the Python version
+  guards unconditional (since the ``contextlib2`` API is the same on all
+  supported versions)
+* changes made to ``docs/contextlib2.rst`` to use ``contextlib2`` version
+  numbers in the version added/changed notes and to integrate the module
+  documentation with the rest of the project documentation
+
+
diff --git a/contrib/python/contextlib2/py3/.dist-info/top_level.txt b/contrib/python/contextlib2/py3/.dist-info/top_level.txt
new file mode 100644
index 0000000000..03fdf8ed24
--- /dev/null
+++ b/contrib/python/contextlib2/py3/.dist-info/top_level.txt
@@ -0,0 +1 @@
+contextlib2
diff --git a/contrib/python/contextlib2/py3/LICENSE.txt b/contrib/python/contextlib2/py3/LICENSE.txt
new file mode 100644
index 0000000000..e40caa18c3
--- /dev/null
+++ b/contrib/python/contextlib2/py3/LICENSE.txt
@@ -0,0 +1,124 @@
+Note: The type hints included in this package come from the typeshed project,
+and are hence distributed under the Apache License 2.0 rather than under the
+Python Software License that covers the module implementation and test suite.
+
+A. HISTORY OF THE SOFTWARE
+==========================
+
+contextlib2 is a derivative of the contextlib module distributed by the PSF
+as part of the Python standard library. According, it is itself redistributed
+under the PSF license (reproduced in full below). As the contextlib module
+was added only in Python 2.5, the licenses for earlier Python versions are
+not applicable and have not been included.
+
+Python was created in the early 1990s by Guido van Rossum at Stichting
+Mathematisch Centrum (CWI, see http://www.cwi.nl) in the Netherlands
+as a successor of a language called ABC.  Guido remains Python's
+principal author, although it includes many contributions from others.
+
+In 1995, Guido continued his work on Python at the Corporation for
+National Research Initiatives (CNRI, see http://www.cnri.reston.va.us)
+in Reston, Virginia where he released several versions of the
+software.
+
+In May 2000, Guido and the Python core development team moved to
+BeOpen.com to form the BeOpen PythonLabs team.  In October of the same
+year, the PythonLabs team moved to Digital Creations (now Zope
+Corporation, see http://www.zope.com).  In 2001, the Python Software
+Foundation (PSF, see http://www.python.org/psf/) was formed, a
+non-profit organization created specifically to own Python-related
+Intellectual Property.  Zope Corporation is a sponsoring member of
+the PSF.
+
+All Python releases are Open Source (see http://www.opensource.org for
+the Open Source Definition).  Historically, most, but not all, Python
+releases have also been GPL-compatible; the table below summarizes
+the various releases that included the contextlib module.
+
+    Release         Derived     Year        Owner       GPL-
+                    from                                compatible? (1)
+
+    2.5             2.4         2006        PSF         yes
+    2.5.1           2.5         2007        PSF         yes
+    2.5.2           2.5.1       2008        PSF         yes
+    2.5.3           2.5.2       2008        PSF         yes
+    2.6             2.5         2008        PSF         yes
+    2.6.1           2.6         2008        PSF         yes
+    2.6.2           2.6.1       2009        PSF         yes
+    2.6.3           2.6.2       2009        PSF         yes
+    2.6.4           2.6.3       2009        PSF         yes
+    2.6.5           2.6.4       2010        PSF         yes
+    3.0             2.6         2008        PSF         yes
+    3.0.1           3.0         2009        PSF         yes
+    3.1             3.0.1       2009        PSF         yes
+    3.1.1           3.1         2009        PSF         yes
+    3.1.2           3.1.1       2010        PSF         yes
+    3.1.3           3.1.2       2010        PSF         yes
+    3.1.4           3.1.3       2011        PSF         yes
+    3.2             3.1         2011        PSF         yes
+    3.2.1           3.2         2011        PSF         yes
+    3.2.2           3.2.1       2011        PSF         yes
+    3.3             3.2         2012        PSF         yes
+
+Footnotes:
+
+(1) GPL-compatible doesn't mean that we're distributing Python under
+    the GPL.  All Python licenses, unlike the GPL, let you distribute
+    a modified version without making your changes open source.  The
+    GPL-compatible licenses make it possible to combine Python with
+    other software that is released under the GPL; the others don't.
+
+Thanks to the many outside volunteers who have worked under Guido's
+direction to make these releases possible.
+
+
+B. TERMS AND CONDITIONS FOR ACCESSING OR OTHERWISE USING PYTHON
+===============================================================
+
+PYTHON SOFTWARE FOUNDATION LICENSE VERSION 2
+--------------------------------------------
+
+1. This LICENSE AGREEMENT is between the Python Software Foundation
+("PSF"), and the Individual or Organization ("Licensee") accessing and
+otherwise using this software ("Python") in source or binary form and
+its associated documentation.
+
+2. Subject to the terms and conditions of this License Agreement, PSF hereby
+grants Licensee a nonexclusive, royalty-free, world-wide license to reproduce,
+analyze, test, perform and/or display publicly, prepare derivative works,
+distribute, and otherwise use Python alone or in any derivative version,
+provided, however, that PSF's License Agreement and PSF's notice of copyright,
+i.e., "Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
+2011 Python Software Foundation; All Rights Reserved" are retained in Python
+alone or in any derivative version prepared by Licensee.
+
+3. In the event Licensee prepares a derivative work that is based on
+or incorporates Python or any part thereof, and wants to make
+the derivative work available to others as provided herein, then
+Licensee hereby agrees to include in any such work a brief summary of
+the changes made to Python.
+
+4. PSF is making Python available to Licensee on an "AS IS"
+basis.  PSF MAKES NO REPRESENTATIONS OR WARRANTIES, EXPRESS OR
+IMPLIED.  BY WAY OF EXAMPLE, BUT NOT LIMITATION, PSF MAKES NO AND
+DISCLAIMS ANY REPRESENTATION OR WARRANTY OF MERCHANTABILITY OR FITNESS
+FOR ANY PARTICULAR PURPOSE OR THAT THE USE OF PYTHON WILL NOT
+INFRINGE ANY THIRD PARTY RIGHTS.
+
+5. PSF SHALL NOT BE LIABLE TO LICENSEE OR ANY OTHER USERS OF PYTHON
+FOR ANY INCIDENTAL, SPECIAL, OR CONSEQUENTIAL DAMAGES OR LOSS AS
+A RESULT OF MODIFYING, DISTRIBUTING, OR OTHERWISE USING PYTHON,
+OR ANY DERIVATIVE THEREOF, EVEN IF ADVISED OF THE POSSIBILITY THEREOF.
+
+6. This License Agreement will automatically terminate upon a material
+breach of its terms and conditions.
+
+7. Nothing in this License Agreement shall be deemed to create any
+relationship of agency, partnership, or joint venture between PSF and
+Licensee.  This License Agreement does not grant permission to use PSF
+trademarks or trade name in a trademark sense to endorse or promote
+products or services of Licensee, or any third party.
+
+8. By copying, installing or otherwise using Python, Licensee
+agrees to be bound by the terms and conditions of this License
+Agreement.
diff --git a/contrib/python/contextlib2/py3/README.rst b/contrib/python/contextlib2/py3/README.rst
new file mode 100644
index 0000000000..6274896e95
--- /dev/null
+++ b/contrib/python/contextlib2/py3/README.rst
@@ -0,0 +1,90 @@
+.. image:: https://jazzband.co/static/img/badge.svg
+   :target: https://jazzband.co/
+   :alt: Jazzband
+
+.. image:: https://github.com/jazzband/contextlib2/workflows/Test/badge.svg
+   :target: https://github.com/jazzband/contextlib2/actions
+   :alt: Tests
+
+.. image:: https://codecov.io/gh/jazzband/contextlib2/branch/master/graph/badge.svg
+   :target: https://codecov.io/gh/jazzband/contextlib2
+   :alt: Coverage
+
+.. image:: https://readthedocs.org/projects/contextlib2/badge/?version=latest
+   :target: https://contextlib2.readthedocs.org/
+   :alt: Latest Docs
+
+contextlib2 is a backport of the `standard library's contextlib
+module <https://docs.python.org/3/library/contextlib.html>`_ to
+earlier Python versions.
+
+It also sometimes serves as a real world proving ground for possible future
+enhancements to the standard library version.
+
+Licensing
+---------
+
+As a backport of Python standard library software, the implementation, test
+suite and other supporting files for this project are distributed under the
+Python Software License used for the CPython reference implementation.
+
+The one exception is the included type hints file, which comes from the
+``typeshed`` project, and is hence distributed under the Apache License 2.0.
+
+Development
+-----------
+
+contextlib2 has no runtime dependencies, but requires ``setuptools`` and
+``wheel`` at build time to generate universal wheel archives.
+
+Local testing is a matter of running::
+
+    python3 -m unittest discover -t . -s test
+
+You can test against multiple versions of Python with
+`tox <https://tox.testrun.org/>`_::
+
+    pip install tox
+    tox
+
+Versions currently tested in both tox and GitHub Actions are:
+
+* CPython 3.6
+* CPython 3.7
+* CPython 3.8
+* CPython 3.9
+* CPython 3.10
+* PyPy3
+
+Updating to a new stdlib reference version
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+As of Python 3.10, 4 files needed to be copied from the CPython reference
+implementation to contextlib2:
+
+* ``Doc/contextlib.rst`` -> ``docs/contextlib2.rst``
+* ``Lib/contextlib.py`` -> ``contextlib2/__init__.py``
+* ``Lib/test/test_contextlib.py`` -> ``test/test_contextlib.py``
+* ``Lib/test/test_contextlib_async.py`` -> ``test/test_contextlib_async.py``
+
+The corresponding version of ``contextlib2/__init__.pyi`` also needs to be
+retrieved from the ``typeshed`` project::
+
+    wget https://raw.githubusercontent.com/python/typeshed/master/stdlib/contextlib.pyi
+
+For the 3.10 sync, the only changes needed to the test files were to import from
+``contextlib2`` rather than ``contextlib``. The test directory is laid out so
+that the test suite's imports from ``test.support`` work the same way they do in
+the main CPython test suite.
+
+The following patch files are saved in the ``dev`` directory:
+
+* changes made to ``contextlib2/__init__.py`` to get it to run on the older
+  versions (and to add back in the deprecated APIs that never graduated to
+  the standard library version)
+* changes made to ``contextlib2/__init__.pyi`` to make the Python version
+  guards unconditional (since the ``contextlib2`` API is the same on all
+  supported versions)
+* changes made to ``docs/contextlib2.rst`` to use ``contextlib2`` version
+  numbers in the version added/changed notes and to integrate the module
+  documentation with the rest of the project documentation
diff --git a/contrib/python/contextlib2/py3/contextlib2/__init__.py b/contrib/python/contextlib2/py3/contextlib2/__init__.py
new file mode 100644
index 0000000000..d6c0c4ac4a
--- /dev/null
+++ b/contrib/python/contextlib2/py3/contextlib2/__init__.py
@@ -0,0 +1,798 @@
+"""contextlib2 - backports and enhancements to the contextlib module"""
+
+import abc
+import sys
+import warnings
+import _collections_abc
+from collections import deque
+from functools import wraps
+from types import MethodType
+
+# Python 3.6/3.7/3.8 compatibility: GenericAlias may not be defined
+try:
+    from types import GenericAlias
+except ImportError:
+    # If the real GenericAlias type doesn't exist, __class_getitem__ won't be used,
+    # so the fallback placeholder doesn't need to provide any meaningful behaviour
+    class GenericAlias:
+        pass
+
+
+__all__ = ["asynccontextmanager", "contextmanager", "closing", "nullcontext",
+           "AbstractContextManager", "AbstractAsyncContextManager",
+           "AsyncExitStack", "ContextDecorator", "ExitStack",
+           "redirect_stdout", "redirect_stderr", "suppress", "aclosing"]
+
+# Backwards compatibility
+__all__ += ["ContextStack"]
+
+class AbstractContextManager(abc.ABC):
+    """An abstract base class for context managers."""
+
+    __class_getitem__ = classmethod(GenericAlias)
+
+    def __enter__(self):
+        """Return `self` upon entering the runtime context."""
+        return self
+
+    @abc.abstractmethod
+    def __exit__(self, exc_type, exc_value, traceback):
+        """Raise any exception triggered within the runtime context."""
+        return None
+
+    @classmethod
+    def __subclasshook__(cls, C):
+        if cls is AbstractContextManager:
+            return _collections_abc._check_methods(C, "__enter__", "__exit__")
+        return NotImplemented
+
+
+class AbstractAsyncContextManager(abc.ABC):
+
+    """An abstract base class for asynchronous context managers."""
+
+    __class_getitem__ = classmethod(GenericAlias)
+
+    async def __aenter__(self):
+        """Return `self` upon entering the runtime context."""
+        return self
+
+    @abc.abstractmethod
+    async def __aexit__(self, exc_type, exc_value, traceback):
+        """Raise any exception triggered within the runtime context."""
+        return None
+
+    @classmethod
+    def __subclasshook__(cls, C):
+        if cls is AbstractAsyncContextManager:
+            return _collections_abc._check_methods(C, "__aenter__",
+                                                   "__aexit__")
+        return NotImplemented
+
+
+class ContextDecorator(object):
+    "A base class or mixin that enables context managers to work as decorators."
+
+    def refresh_cm(self):
+        """Returns the context manager used to actually wrap the call to the
+        decorated function.
+
+        The default implementation just returns *self*.
+
+        Overriding this method allows otherwise one-shot context managers
+        like _GeneratorContextManager to support use as decorators via
+        implicit recreation.
+
+        DEPRECATED: refresh_cm was never added to the standard library's
+                    ContextDecorator API
+        """
+        warnings.warn("refresh_cm was never added to the standard library",
+                      DeprecationWarning)
+        return self._recreate_cm()
+
+    def _recreate_cm(self):
+        """Return a recreated instance of self.
+
+        Allows an otherwise one-shot context manager like
+        _GeneratorContextManager to support use as
+        a decorator via implicit recreation.
+
+        This is a private interface just for _GeneratorContextManager.
+        See issue #11647 for details.
+        """
+        return self
+
+    def __call__(self, func):
+        @wraps(func)
+        def inner(*args, **kwds):
+            with self._recreate_cm():
+                return func(*args, **kwds)
+        return inner
+
+
+class AsyncContextDecorator(object):
+    "A base class or mixin that enables async context managers to work as decorators."
+
+    def _recreate_cm(self):
+        """Return a recreated instance of self.
+        """
+        return self
+
+    def __call__(self, func):
+        @wraps(func)
+        async def inner(*args, **kwds):
+            async with self._recreate_cm():
+                return await func(*args, **kwds)
+        return inner
+
+
+class _GeneratorContextManagerBase:
+    """Shared functionality for @contextmanager and @asynccontextmanager."""
+
+    def __init__(self, func, args, kwds):
+        self.gen = func(*args, **kwds)
+        self.func, self.args, self.kwds = func, args, kwds
+        # Issue 19330: ensure context manager instances have good docstrings
+        doc = getattr(func, "__doc__", None)
+        if doc is None:
+            doc = type(self).__doc__
+        self.__doc__ = doc
+        # Unfortunately, this still doesn't provide good help output when
+        # inspecting the created context manager instances, since pydoc
+        # currently bypasses the instance docstring and shows the docstring
+        # for the class instead.
+        # See http://bugs.python.org/issue19404 for more details.
+
+
+class _GeneratorContextManager(_GeneratorContextManagerBase,
+                               AbstractContextManager,
+                               ContextDecorator):
+    """Helper for @contextmanager decorator."""
+
+    def _recreate_cm(self):
+        # _GCM instances are one-shot context managers, so the
+        # CM must be recreated each time a decorated function is
+        # called
+        return self.__class__(self.func, self.args, self.kwds)
+
+    def __enter__(self):
+        # do not keep args and kwds alive unnecessarily
+        # they are only needed for recreation, which is not possible anymore
+        del self.args, self.kwds, self.func
+        try:
+            return next(self.gen)
+        except StopIteration:
+            raise RuntimeError("generator didn't yield") from None
+
+    def __exit__(self, type, value, traceback):
+        if type is None:
+            try:
+                next(self.gen)
+            except StopIteration:
+                return False
+            else:
+                raise RuntimeError("generator didn't stop")
+        else:
+            if value is None:
+                # Need to force instantiation so we can reliably
+                # tell if we get the same exception back
+                value = type()
+            try:
+                self.gen.throw(type, value, traceback)
+            except StopIteration as exc:
+                # Suppress StopIteration *unless* it's the same exception that
+                # was passed to throw().  This prevents a StopIteration
+                # raised inside the "with" statement from being suppressed.
+                return exc is not value
+            except RuntimeError as exc:
+                # Don't re-raise the passed in exception. (issue27122)
+                if exc is value:
+                    return False
+                # Likewise, avoid suppressing if a StopIteration exception
+                # was passed to throw() and later wrapped into a RuntimeError
+                # (see PEP 479).
+                if type is StopIteration and exc.__cause__ is value:
+                    return False
+                raise
+            except:
+                # only re-raise if it's *not* the exception that was
+                # passed to throw(), because __exit__() must not raise
+                # an exception unless __exit__() itself failed.  But throw()
+                # has to raise the exception to signal propagation, so this
+                # fixes the impedance mismatch between the throw() protocol
+                # and the __exit__() protocol.
+                #
+                # This cannot use 'except BaseException as exc' (as in the
+                # async implementation) to maintain compatibility with
+                # Python 2, where old-style class exceptions are not caught
+                # by 'except BaseException'.
+                if sys.exc_info()[1] is value:
+                    return False
+                raise
+            raise RuntimeError("generator didn't stop after throw()")
+
+
+class _AsyncGeneratorContextManager(_GeneratorContextManagerBase,
+                                    AbstractAsyncContextManager,
+                                    AsyncContextDecorator):
+    """Helper for @asynccontextmanager."""
+
+    def _recreate_cm(self):
+        # _AGCM instances are one-shot context managers, so the
+        # ACM must be recreated each time a decorated function is
+        # called
+        return self.__class__(self.func, self.args, self.kwds)
+
+    async def __aenter__(self):
+        try:
+            return await self.gen.__anext__()
+        except StopAsyncIteration:
+            raise RuntimeError("generator didn't yield") from None
+
+    async def __aexit__(self, typ, value, traceback):
+        if typ is None:
+            try:
+                await self.gen.__anext__()
+            except StopAsyncIteration:
+                return
+            else:
+                raise RuntimeError("generator didn't stop")
+        else:
+            if value is None:
+                value = typ()
+            # See _GeneratorContextManager.__exit__ for comments on subtleties
+            # in this implementation
+            try:
+                await self.gen.athrow(typ, value, traceback)
+                raise RuntimeError("generator didn't stop after athrow()")
+            except StopAsyncIteration as exc:
+                return exc is not value
+            except RuntimeError as exc:
+                if exc is value:
+                    return False
+                # Avoid suppressing if a StopIteration exception
+                # was passed to throw() and later wrapped into a RuntimeError
+                # (see PEP 479 for sync generators; async generators also
+                # have this behavior). But do this only if the exception wrapped
+                # by the RuntimeError is actually Stop(Async)Iteration (see
+                # issue29692).
+                if isinstance(value, (StopIteration, StopAsyncIteration)):
+                    if exc.__cause__ is value:
+                        return False
+                raise
+            except BaseException as exc:
+                if exc is not value:
+                    raise
+
+
+def contextmanager(func):
+    """@contextmanager decorator.
+
+    Typical usage:
+
+        @contextmanager
+        def some_generator(<arguments>):
+            <setup>
+            try:
+                yield <value>
+            finally:
+                <cleanup>
+
+    This makes this:
+
+        with some_generator(<arguments>) as <variable>:
+            <body>
+
+    equivalent to this:
+
+        <setup>
+        try:
+            <variable> = <value>
+            <body>
+        finally:
+            <cleanup>
+    """
+    @wraps(func)
+    def helper(*args, **kwds):
+        return _GeneratorContextManager(func, args, kwds)
+    return helper
+
+
+def asynccontextmanager(func):
+    """@asynccontextmanager decorator.
+
+    Typical usage:
+
+        @asynccontextmanager
+        async def some_async_generator(<arguments>):
+            <setup>
+            try:
+                yield <value>
+            finally:
+                <cleanup>
+
+    This makes this:
+
+        async with some_async_generator(<arguments>) as <variable>:
+            <body>
+
+    equivalent to this:
+
+        <setup>
+        try:
+            <variable> = <value>
+            <body>
+        finally:
+            <cleanup>
+    """
+    @wraps(func)
+    def helper(*args, **kwds):
+        return _AsyncGeneratorContextManager(func, args, kwds)
+    return helper
+
+
+class closing(AbstractContextManager):
+    """Context to automatically close something at the end of a block.
+
+    Code like this:
+
+        with closing(<module>.open(<arguments>)) as f:
+            <block>
+
+    is equivalent to this:
+
+        f = <module>.open(<arguments>)
+        try:
+            <block>
+        finally:
+            f.close()
+
+    """
+    def __init__(self, thing):
+        self.thing = thing
+    def __enter__(self):
+        return self.thing
+    def __exit__(self, *exc_info):
+        self.thing.close()
+
+
+class aclosing(AbstractAsyncContextManager):
+    """Async context manager for safely finalizing an asynchronously cleaned-up
+    resource such as an async generator, calling its ``aclose()`` method.
+
+    Code like this:
+
+        async with aclosing(<module>.fetch(<arguments>)) as agen:
+            <block>
+
+    is equivalent to this:
+
+        agen = <module>.fetch(<arguments>)
+        try:
+            <block>
+        finally:
+            await agen.aclose()
+
+    """
+    def __init__(self, thing):
+        self.thing = thing
+    async def __aenter__(self):
+        return self.thing
+    async def __aexit__(self, *exc_info):
+        await self.thing.aclose()
+
+
+class _RedirectStream(AbstractContextManager):
+
+    _stream = None
+
+    def __init__(self, new_target):
+        self._new_target = new_target
+        # We use a list of old targets to make this CM re-entrant
+        self._old_targets = []
+
+    def __enter__(self):
+        self._old_targets.append(getattr(sys, self._stream))
+        setattr(sys, self._stream, self._new_target)
+        return self._new_target
+
+    def __exit__(self, exctype, excinst, exctb):
+        setattr(sys, self._stream, self._old_targets.pop())
+
+
+class redirect_stdout(_RedirectStream):
+    """Context manager for temporarily redirecting stdout to another file.
+
+        # How to send help() to stderr
+        with redirect_stdout(sys.stderr):
+            help(dir)
+
+        # How to write help() to a file
+        with open('help.txt', 'w') as f:
+            with redirect_stdout(f):
+                help(pow)
+    """
+
+    _stream = "stdout"
+
+
+class redirect_stderr(_RedirectStream):
+    """Context manager for temporarily redirecting stderr to another file."""
+
+    _stream = "stderr"
+
+
+class suppress(AbstractContextManager):
+    """Context manager to suppress specified exceptions
+
+    After the exception is suppressed, execution proceeds with the next
+    statement following the with statement.
+
+         with suppress(FileNotFoundError):
+             os.remove(somefile)
+         # Execution still resumes here if the file was already removed
+    """
+
+    def __init__(self, *exceptions):
+        self._exceptions = exceptions
+
+    def __enter__(self):
+        pass
+
+    def __exit__(self, exctype, excinst, exctb):
+        # Unlike isinstance and issubclass, CPython exception handling
+        # currently only looks at the concrete type hierarchy (ignoring
+        # the instance and subclass checking hooks). While Guido considers
+        # that a bug rather than a feature, it's a fairly hard one to fix
+        # due to various internal implementation details. suppress provides
+        # the simpler issubclass based semantics, rather than trying to
+        # exactly reproduce the limitations of the CPython interpreter.
+        #
+        # See http://bugs.python.org/issue12029 for more details
+        return exctype is not None and issubclass(exctype, self._exceptions)
+
+
+class _BaseExitStack:
+    """A base class for ExitStack and AsyncExitStack."""
+
+    @staticmethod
+    def _create_exit_wrapper(cm, cm_exit):
+        return MethodType(cm_exit, cm)
+
+    @staticmethod
+    def _create_cb_wrapper(*args, **kwds):
+        # Python 3.6/3.7 compatibility: no native positional-only args syntax
+        callback, *args = args
+        def _exit_wrapper(exc_type, exc, tb):
+            callback(*args, **kwds)
+        return _exit_wrapper
+
+    def __init__(self):
+        self._exit_callbacks = deque()
+
+    def pop_all(self):
+        """Preserve the context stack by transferring it to a new instance."""
+        new_stack = type(self)()
+        new_stack._exit_callbacks = self._exit_callbacks
+        self._exit_callbacks = deque()
+        return new_stack
+
+    def push(self, exit):
+        """Registers a callback with the standard __exit__ method signature.
+
+        Can suppress exceptions the same way __exit__ method can.
+        Also accepts any object with an __exit__ method (registering a call
+        to the method instead of the object itself).
+        """
+        # We use an unbound method rather than a bound method to follow
+        # the standard lookup behaviour for special methods.
+        _cb_type = type(exit)
+
+        try:
+            exit_method = _cb_type.__exit__
+        except AttributeError:
+            # Not a context manager, so assume it's a callable.
+            self._push_exit_callback(exit)
+        else:
+            self._push_cm_exit(exit, exit_method)
+        return exit  # Allow use as a decorator.
+
+    def enter_context(self, cm):
+        """Enters the supplied context manager.
+
+        If successful, also pushes its __exit__ method as a callback and
+        returns the result of the __enter__ method.
+        """
+        # We look up the special methods on the type to match the with
+        # statement.
+        _cm_type = type(cm)
+        _exit = _cm_type.__exit__
+        result = _cm_type.__enter__(cm)
+        self._push_cm_exit(cm, _exit)
+        return result
+
+    def callback(*args, **kwds):
+        """Registers an arbitrary callback and arguments.
+
+        Cannot suppress exceptions.
+        """
+        # Python 3.6/3.7 compatibility: no native positional-only args syntax
+        try:
+            self, callback, *args = args
+        except ValueError as exc:
+            exc_details = str(exc).partition("(")[2]
+            msg = "Not enough positional arguments {}".format(exc_details)
+            raise TypeError(msg) from None
+        _exit_wrapper = self._create_cb_wrapper(callback, *args, **kwds)
+
+        # We changed the signature, so using @wraps is not appropriate, but
+        # setting __wrapped__ may still help with introspection.
+        _exit_wrapper.__wrapped__ = callback
+        self._push_exit_callback(_exit_wrapper)
+        return callback  # Allow use as a decorator
+
+    def _push_cm_exit(self, cm, cm_exit):
+        """Helper to correctly register callbacks to __exit__ methods."""
+        _exit_wrapper = self._create_exit_wrapper(cm, cm_exit)
+        self._push_exit_callback(_exit_wrapper, True)
+
+    def _push_exit_callback(self, callback, is_sync=True):
+        self._exit_callbacks.append((is_sync, callback))
+
+
+# Inspired by discussions on http://bugs.python.org/issue13585
+class ExitStack(_BaseExitStack, AbstractContextManager):
+    """Context manager for dynamic management of a stack of exit callbacks.
+
+    For example:
+        with ExitStack() as stack:
+            files = [stack.enter_context(open(fname)) for fname in filenames]
+            # All opened files will automatically be closed at the end of
+            # the with statement, even if attempts to open files later
+            # in the list raise an exception.
+    """
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *exc_details):
+        received_exc = exc_details[0] is not None
+
+        # We manipulate the exception state so it behaves as though
+        # we were actually nesting multiple with statements
+        frame_exc = sys.exc_info()[1]
+        def _fix_exception_context(new_exc, old_exc):
+            # Context may not be correct, so find the end of the chain
+            while 1:
+                exc_context = new_exc.__context__
+                if exc_context is old_exc:
+                    # Context is already set correctly (see issue 20317)
+                    return
+                if exc_context is None or exc_context is frame_exc:
+                    break
+                new_exc = exc_context
+            # Change the end of the chain to point to the exception
+            # we expect it to reference
+            new_exc.__context__ = old_exc
+
+        # Callbacks are invoked in LIFO order to match the behaviour of
+        # nested context managers
+        suppressed_exc = False
+        pending_raise = False
+        while self._exit_callbacks:
+            is_sync, cb = self._exit_callbacks.pop()
+            assert is_sync
+            try:
+                if cb(*exc_details):
+                    suppressed_exc = True
+                    pending_raise = False
+                    exc_details = (None, None, None)
+            except:
+                new_exc_details = sys.exc_info()
+                # simulate the stack of exceptions by setting the context
+                _fix_exception_context(new_exc_details[1], exc_details[1])
+                pending_raise = True
+                exc_details = new_exc_details
+        if pending_raise:
+            try:
+                # bare "raise exc_details[1]" replaces our carefully
+                # set-up context
+                fixed_ctx = exc_details[1].__context__
+                raise exc_details[1]
+            except BaseException:
+                exc_details[1].__context__ = fixed_ctx
+                raise
+        return received_exc and suppressed_exc
+
+    def close(self):
+        """Immediately unwind the context stack."""
+        self.__exit__(None, None, None)
+
+
+# Inspired by discussions on https://bugs.python.org/issue29302
+class AsyncExitStack(_BaseExitStack, AbstractAsyncContextManager):
+    """Async context manager for dynamic management of a stack of exit
+    callbacks.
+
+    For example:
+        async with AsyncExitStack() as stack:
+            connections = [await stack.enter_async_context(get_connection())
+                for i in range(5)]
+            # All opened connections will automatically be released at the
+            # end of the async with statement, even if attempts to open a
+            # connection later in the list raise an exception.
+    """
+
+    @staticmethod
+    def _create_async_exit_wrapper(cm, cm_exit):
+        return MethodType(cm_exit, cm)
+
+    @staticmethod
+    def _create_async_cb_wrapper(*args, **kwds):
+        # Python 3.6/3.7 compatibility: no native positional-only args syntax
+        callback, *args = args
+        async def _exit_wrapper(exc_type, exc, tb):
+            await callback(*args, **kwds)
+        return _exit_wrapper
+
+    async def enter_async_context(self, cm):
+        """Enters the supplied async context manager.
+
+        If successful, also pushes its __aexit__ method as a callback and
+        returns the result of the __aenter__ method.
+        """
+        _cm_type = type(cm)
+        _exit = _cm_type.__aexit__
+        result = await _cm_type.__aenter__(cm)
+        self._push_async_cm_exit(cm, _exit)
+        return result
+
+    def push_async_exit(self, exit):
+        """Registers a coroutine function with the standard __aexit__ method
+        signature.
+
+        Can suppress exceptions the same way __aexit__ method can.
+        Also accepts any object with an __aexit__ method (registering a call
+        to the method instead of the object itself).
+        """
+        _cb_type = type(exit)
+        try:
+            exit_method = _cb_type.__aexit__
+        except AttributeError:
+            # Not an async context manager, so assume it's a coroutine function
+            self._push_exit_callback(exit, False)
+        else:
+            self._push_async_cm_exit(exit, exit_method)
+        return exit  # Allow use as a decorator
+
+    def push_async_callback(*args, **kwds):
+        """Registers an arbitrary coroutine function and arguments.
+
+        Cannot suppress exceptions.
+        """
+        # Python 3.6/3.7 compatibility: no native positional-only args syntax
+        try:
+            self, callback, *args = args
+        except ValueError as exc:
+            exc_details = str(exc).partition("(")[2]
+            msg = "Not enough positional arguments {}".format(exc_details)
+            raise TypeError(msg) from None
+        _exit_wrapper = self._create_async_cb_wrapper(callback, *args, **kwds)
+
+        # We changed the signature, so using @wraps is not appropriate, but
+        # setting __wrapped__ may still help with introspection.
+        _exit_wrapper.__wrapped__ = callback
+        self._push_exit_callback(_exit_wrapper, False)
+        return callback  # Allow use as a decorator
+
+    async def aclose(self):
+        """Immediately unwind the context stack."""
+        await self.__aexit__(None, None, None)
+
+    def _push_async_cm_exit(self, cm, cm_exit):
+        """Helper to correctly register coroutine function to __aexit__
+        method."""
+        _exit_wrapper = self._create_async_exit_wrapper(cm, cm_exit)
+        self._push_exit_callback(_exit_wrapper, False)
+
+    async def __aenter__(self):
+        return self
+
+    async def __aexit__(self, *exc_details):
+        received_exc = exc_details[0] is not None
+
+        # We manipulate the exception state so it behaves as though
+        # we were actually nesting multiple with statements
+        frame_exc = sys.exc_info()[1]
+        def _fix_exception_context(new_exc, old_exc):
+            # Context may not be correct, so find the end of the chain
+            while 1:
+                exc_context = new_exc.__context__
+                if exc_context is old_exc:
+                    # Context is already set correctly (see issue 20317)
+                    return
+                if exc_context is None or exc_context is frame_exc:
+                    break
+                new_exc = exc_context
+            # Change the end of the chain to point to the exception
+            # we expect it to reference
+            new_exc.__context__ = old_exc
+
+        # Callbacks are invoked in LIFO order to match the behaviour of
+        # nested context managers
+        suppressed_exc = False
+        pending_raise = False
+        while self._exit_callbacks:
+            is_sync, cb = self._exit_callbacks.pop()
+            try:
+                if is_sync:
+                    cb_suppress = cb(*exc_details)
+                else:
+                    cb_suppress = await cb(*exc_details)
+
+                if cb_suppress:
+                    suppressed_exc = True
+                    pending_raise = False
+                    exc_details = (None, None, None)
+            except:
+                new_exc_details = sys.exc_info()
+                # simulate the stack of exceptions by setting the context
+                _fix_exception_context(new_exc_details[1], exc_details[1])
+                pending_raise = True
+                exc_details = new_exc_details
+        if pending_raise:
+            try:
+                # bare "raise exc_details[1]" replaces our carefully
+                # set-up context
+                fixed_ctx = exc_details[1].__context__
+                raise exc_details[1]
+            except BaseException:
+                exc_details[1].__context__ = fixed_ctx
+                raise
+        return received_exc and suppressed_exc
+
+
+class nullcontext(AbstractContextManager, AbstractAsyncContextManager):
+    """Context manager that does no additional processing.
+
+    Used as a stand-in for a normal context manager, when a particular
+    block of code is only sometimes used with a normal context manager:
+
+    cm = optional_cm if condition else nullcontext()
+    with cm:
+        # Perform operation, using optional_cm if condition is True
+    """
+
+    def __init__(self, enter_result=None):
+        self.enter_result = enter_result
+
+    def __enter__(self):
+        return self.enter_result
+
+    def __exit__(self, *excinfo):
+        pass
+
+    async def __aenter__(self):
+        return self.enter_result
+
+    async def __aexit__(self, *excinfo):
+        pass
+
+
+# Preserve backwards compatibility
+class ContextStack(ExitStack):
+    """Backwards compatibility alias for ExitStack"""
+
+    def __init__(self):
+        warnings.warn("ContextStack has been renamed to ExitStack",
+                      DeprecationWarning)
+        super(ContextStack, self).__init__()
+
+    def register_exit(self, callback):
+        return self.push(callback)
+
+    def register(self, callback, *args, **kwds):
+        return self.callback(callback, *args, **kwds)
+
+    def preserve(self):
+        return self.pop_all()
diff --git a/contrib/python/contextlib2/py3/contextlib2/py.typed b/contrib/python/contextlib2/py3/contextlib2/py.typed
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/contrib/python/contextlib2/py3/contextlib2/py.typed
diff --git a/contrib/python/contextlib2/py3/ya.make b/contrib/python/contextlib2/py3/ya.make
new file mode 100644
index 0000000000..9674bb12d4
--- /dev/null
+++ b/contrib/python/contextlib2/py3/ya.make
@@ -0,0 +1,24 @@
+# Generated by devtools/yamaker (pypi).
+
+PY3_LIBRARY()
+
+VERSION(21.6.0)
+
+LICENSE(PSF-2.0)
+
+NO_LINT()
+
+PY_SRCS(
+    TOP_LEVEL
+    contextlib2/__init__.py
+    contextlib2/__init__.pyi
+)
+
+RESOURCE_FILES(
+    PREFIX contrib/python/contextlib2/py3/
+    .dist-info/METADATA
+    .dist-info/top_level.txt
+    contextlib2/py.typed
+)
+
+END()
diff --git a/contrib/python/contextlib2/ya.make b/contrib/python/contextlib2/ya.make
new file mode 100644
index 0000000000..00b1b55ba1
--- /dev/null
+++ b/contrib/python/contextlib2/ya.make
@@ -0,0 +1,18 @@
+PY23_LIBRARY()
+
+LICENSE(Service-Py23-Proxy)
+
+IF (PYTHON2)
+    PEERDIR(contrib/python/contextlib2/py2)
+ELSE()
+    PEERDIR(contrib/python/contextlib2/py3)
+ENDIF()
+
+NO_LINT()
+
+END()
+
+RECURSE(
+    py2
+    py3
+)