Update prebuilt Clang to r416183b from Android.

https://android.googlesource.com/platform/prebuilts/clang/host/
linux-x86/+/06a71ddac05c22edb2d10b590e1769b3f8619bef

clang 12.0.5 (based on r416183b) from build 7284624.

Change-Id: I277a316abcf47307562d8b748b84870f31a72866
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/linux-x64/clang/python3/lib/python3.9/inspect.py b/linux-x64/clang/python3/lib/python3.9/inspect.py
new file mode 100644
index 0000000..18bed90
--- /dev/null
+++ b/linux-x64/clang/python3/lib/python3.9/inspect.py
@@ -0,0 +1,3192 @@
+"""Get useful information from live Python objects.
+
+This module encapsulates the interface provided by the internal special
+attributes (co_*, im_*, tb_*, etc.) in a friendlier fashion.
+It also provides some help for examining source code and class layout.
+
+Here are some of the useful functions provided by this module:
+
+    ismodule(), isclass(), ismethod(), isfunction(), isgeneratorfunction(),
+        isgenerator(), istraceback(), isframe(), iscode(), isbuiltin(),
+        isroutine() - check object types
+    getmembers() - get members of an object that satisfy a given condition
+
+    getfile(), getsourcefile(), getsource() - find an object's source code
+    getdoc(), getcomments() - get documentation on an object
+    getmodule() - determine the module that an object came from
+    getclasstree() - arrange classes so as to represent their hierarchy
+
+    getargvalues(), getcallargs() - get info about function arguments
+    getfullargspec() - same, with support for Python 3 features
+    formatargvalues() - format an argument spec
+    getouterframes(), getinnerframes() - get info about frames
+    currentframe() - get the current stack frame
+    stack(), trace() - get info about frames on the stack or in a traceback
+
+    signature() - get a Signature object for the callable
+"""
+
+# This module is in the public domain.  No warranties.
+
+__author__ = ('Ka-Ping Yee <ping@lfw.org>',
+              'Yury Selivanov <yselivanov@sprymix.com>')
+
+import abc
+import ast
+import dis
+import collections.abc
+import enum
+import importlib.machinery
+import itertools
+import linecache
+import os
+import re
+import sys
+import tokenize
+import token
+import types
+import warnings
+import functools
+import builtins
+from operator import attrgetter
+from collections import namedtuple, OrderedDict
+
+# Create constants for the compiler flags in Include/code.h
+# We try to get them from dis to avoid duplication
+mod_dict = globals()
+for k, v in dis.COMPILER_FLAG_NAMES.items():
+    mod_dict["CO_" + v] = k
+
+# See Include/object.h
+TPFLAGS_IS_ABSTRACT = 1 << 20
+
+# ----------------------------------------------------------- type-checking
+def ismodule(object):
+    """Return true if the object is a module.
+
+    Module objects provide these attributes:
+        __cached__      pathname to byte compiled file
+        __doc__         documentation string
+        __file__        filename (missing for built-in modules)"""
+    return isinstance(object, types.ModuleType)
+
+def isclass(object):
+    """Return true if the object is a class.
+
+    Class objects provide these attributes:
+        __doc__         documentation string
+        __module__      name of module in which this class was defined"""
+    return isinstance(object, type)
+
+def ismethod(object):
+    """Return true if the object is an instance method.
+
+    Instance method objects provide these attributes:
+        __doc__         documentation string
+        __name__        name with which this method was defined
+        __func__        function object containing implementation of method
+        __self__        instance to which this method is bound"""
+    return isinstance(object, types.MethodType)
+
+def ismethoddescriptor(object):
+    """Return true if the object is a method descriptor.
+
+    But not if ismethod() or isclass() or isfunction() are true.
+
+    This is new in Python 2.2, and, for example, is true of int.__add__.
+    An object passing this test has a __get__ attribute but not a __set__
+    attribute, but beyond that the set of attributes varies.  __name__ is
+    usually sensible, and __doc__ often is.
+
+    Methods implemented via descriptors that also pass one of the other
+    tests return false from the ismethoddescriptor() test, simply because
+    the other tests promise more -- you can, e.g., count on having the
+    __func__ attribute (etc) when an object passes ismethod()."""
+    if isclass(object) or ismethod(object) or isfunction(object):
+        # mutual exclusion
+        return False
+    tp = type(object)
+    return hasattr(tp, "__get__") and not hasattr(tp, "__set__")
+
+def isdatadescriptor(object):
+    """Return true if the object is a data descriptor.
+
+    Data descriptors have a __set__ or a __delete__ attribute.  Examples are
+    properties (defined in Python) and getsets and members (defined in C).
+    Typically, data descriptors will also have __name__ and __doc__ attributes
+    (properties, getsets, and members have both of these attributes), but this
+    is not guaranteed."""
+    if isclass(object) or ismethod(object) or isfunction(object):
+        # mutual exclusion
+        return False
+    tp = type(object)
+    return hasattr(tp, "__set__") or hasattr(tp, "__delete__")
+
+if hasattr(types, 'MemberDescriptorType'):
+    # CPython and equivalent
+    def ismemberdescriptor(object):
+        """Return true if the object is a member descriptor.
+
+        Member descriptors are specialized descriptors defined in extension
+        modules."""
+        return isinstance(object, types.MemberDescriptorType)
+else:
+    # Other implementations
+    def ismemberdescriptor(object):
+        """Return true if the object is a member descriptor.
+
+        Member descriptors are specialized descriptors defined in extension
+        modules."""
+        return False
+
+if hasattr(types, 'GetSetDescriptorType'):
+    # CPython and equivalent
+    def isgetsetdescriptor(object):
+        """Return true if the object is a getset descriptor.
+
+        getset descriptors are specialized descriptors defined in extension
+        modules."""
+        return isinstance(object, types.GetSetDescriptorType)
+else:
+    # Other implementations
+    def isgetsetdescriptor(object):
+        """Return true if the object is a getset descriptor.
+
+        getset descriptors are specialized descriptors defined in extension
+        modules."""
+        return False
+
+def isfunction(object):
+    """Return true if the object is a user-defined function.
+
+    Function objects provide these attributes:
+        __doc__         documentation string
+        __name__        name with which this function was defined
+        __code__        code object containing compiled function bytecode
+        __defaults__    tuple of any default values for arguments
+        __globals__     global namespace in which this function was defined
+        __annotations__ dict of parameter annotations
+        __kwdefaults__  dict of keyword only parameters with defaults"""
+    return isinstance(object, types.FunctionType)
+
+def _has_code_flag(f, flag):
+    """Return true if ``f`` is a function (or a method or functools.partial
+    wrapper wrapping a function) whose code object has the given ``flag``
+    set in its flags."""
+    while ismethod(f):
+        f = f.__func__
+    f = functools._unwrap_partial(f)
+    if not isfunction(f):
+        return False
+    return bool(f.__code__.co_flags & flag)
+
+def isgeneratorfunction(obj):
+    """Return true if the object is a user-defined generator function.
+
+    Generator function objects provide the same attributes as functions.
+    See help(isfunction) for a list of attributes."""
+    return _has_code_flag(obj, CO_GENERATOR)
+
+def iscoroutinefunction(obj):
+    """Return true if the object is a coroutine function.
+
+    Coroutine functions are defined with "async def" syntax.
+    """
+    return _has_code_flag(obj, CO_COROUTINE)
+
+def isasyncgenfunction(obj):
+    """Return true if the object is an asynchronous generator function.
+
+    Asynchronous generator functions are defined with "async def"
+    syntax and have "yield" expressions in their body.
+    """
+    return _has_code_flag(obj, CO_ASYNC_GENERATOR)
+
+def isasyncgen(object):
+    """Return true if the object is an asynchronous generator."""
+    return isinstance(object, types.AsyncGeneratorType)
+
+def isgenerator(object):
+    """Return true if the object is a generator.
+
+    Generator objects provide these attributes:
+        __iter__        defined to support iteration over container
+        close           raises a new GeneratorExit exception inside the
+                        generator to terminate the iteration
+        gi_code         code object
+        gi_frame        frame object or possibly None once the generator has
+                        been exhausted
+        gi_running      set to 1 when generator is executing, 0 otherwise
+        next            return the next item from the container
+        send            resumes the generator and "sends" a value that becomes
+                        the result of the current yield-expression
+        throw           used to raise an exception inside the generator"""
+    return isinstance(object, types.GeneratorType)
+
+def iscoroutine(object):
+    """Return true if the object is a coroutine."""
+    return isinstance(object, types.CoroutineType)
+
+def isawaitable(object):
+    """Return true if object can be passed to an ``await`` expression."""
+    return (isinstance(object, types.CoroutineType) or
+            isinstance(object, types.GeneratorType) and
+                bool(object.gi_code.co_flags & CO_ITERABLE_COROUTINE) or
+            isinstance(object, collections.abc.Awaitable))
+
+def istraceback(object):
+    """Return true if the object is a traceback.
+
+    Traceback objects provide these attributes:
+        tb_frame        frame object at this level
+        tb_lasti        index of last attempted instruction in bytecode
+        tb_lineno       current line number in Python source code
+        tb_next         next inner traceback object (called by this level)"""
+    return isinstance(object, types.TracebackType)
+
+def isframe(object):
+    """Return true if the object is a frame object.
+
+    Frame objects provide these attributes:
+        f_back          next outer frame object (this frame's caller)
+        f_builtins      built-in namespace seen by this frame
+        f_code          code object being executed in this frame
+        f_globals       global namespace seen by this frame
+        f_lasti         index of last attempted instruction in bytecode
+        f_lineno        current line number in Python source code
+        f_locals        local namespace seen by this frame
+        f_trace         tracing function for this frame, or None"""
+    return isinstance(object, types.FrameType)
+
+def iscode(object):
+    """Return true if the object is a code object.
+
+    Code objects provide these attributes:
+        co_argcount         number of arguments (not including *, ** args
+                            or keyword only arguments)
+        co_code             string of raw compiled bytecode
+        co_cellvars         tuple of names of cell variables
+        co_consts           tuple of constants used in the bytecode
+        co_filename         name of file in which this code object was created
+        co_firstlineno      number of first line in Python source code
+        co_flags            bitmap: 1=optimized | 2=newlocals | 4=*arg | 8=**arg
+                            | 16=nested | 32=generator | 64=nofree | 128=coroutine
+                            | 256=iterable_coroutine | 512=async_generator
+        co_freevars         tuple of names of free variables
+        co_posonlyargcount  number of positional only arguments
+        co_kwonlyargcount   number of keyword only arguments (not including ** arg)
+        co_lnotab           encoded mapping of line numbers to bytecode indices
+        co_name             name with which this code object was defined
+        co_names            tuple of names of local variables
+        co_nlocals          number of local variables
+        co_stacksize        virtual machine stack space required
+        co_varnames         tuple of names of arguments and local variables"""
+    return isinstance(object, types.CodeType)
+
+def isbuiltin(object):
+    """Return true if the object is a built-in function or method.
+
+    Built-in functions and methods provide these attributes:
+        __doc__         documentation string
+        __name__        original name of this function or method
+        __self__        instance to which a method is bound, or None"""
+    return isinstance(object, types.BuiltinFunctionType)
+
+def isroutine(object):
+    """Return true if the object is any kind of function or method."""
+    return (isbuiltin(object)
+            or isfunction(object)
+            or ismethod(object)
+            or ismethoddescriptor(object))
+
+def isabstract(object):
+    """Return true if the object is an abstract base class (ABC)."""
+    if not isinstance(object, type):
+        return False
+    if object.__flags__ & TPFLAGS_IS_ABSTRACT:
+        return True
+    if not issubclass(type(object), abc.ABCMeta):
+        return False
+    if hasattr(object, '__abstractmethods__'):
+        # It looks like ABCMeta.__new__ has finished running;
+        # TPFLAGS_IS_ABSTRACT should have been accurate.
+        return False
+    # It looks like ABCMeta.__new__ has not finished running yet; we're
+    # probably in __init_subclass__. We'll look for abstractmethods manually.
+    for name, value in object.__dict__.items():
+        if getattr(value, "__isabstractmethod__", False):
+            return True
+    for base in object.__bases__:
+        for name in getattr(base, "__abstractmethods__", ()):
+            value = getattr(object, name, None)
+            if getattr(value, "__isabstractmethod__", False):
+                return True
+    return False
+
+def getmembers(object, predicate=None):
+    """Return all members of an object as (name, value) pairs sorted by name.
+    Optionally, only return members that satisfy a given predicate."""
+    if isclass(object):
+        mro = (object,) + getmro(object)
+    else:
+        mro = ()
+    results = []
+    processed = set()
+    names = dir(object)
+    # :dd any DynamicClassAttributes to the list of names if object is a class;
+    # this may result in duplicate entries if, for example, a virtual
+    # attribute with the same name as a DynamicClassAttribute exists
+    try:
+        for base in object.__bases__:
+            for k, v in base.__dict__.items():
+                if isinstance(v, types.DynamicClassAttribute):
+                    names.append(k)
+    except AttributeError:
+        pass
+    for key in names:
+        # First try to get the value via getattr.  Some descriptors don't
+        # like calling their __get__ (see bug #1785), so fall back to
+        # looking in the __dict__.
+        try:
+            value = getattr(object, key)
+            # handle the duplicate key
+            if key in processed:
+                raise AttributeError
+        except AttributeError:
+            for base in mro:
+                if key in base.__dict__:
+                    value = base.__dict__[key]
+                    break
+            else:
+                # could be a (currently) missing slot member, or a buggy
+                # __dir__; discard and move on
+                continue
+        if not predicate or predicate(value):
+            results.append((key, value))
+        processed.add(key)
+    results.sort(key=lambda pair: pair[0])
+    return results
+
+Attribute = namedtuple('Attribute', 'name kind defining_class object')
+
+def classify_class_attrs(cls):
+    """Return list of attribute-descriptor tuples.
+
+    For each name in dir(cls), the return list contains a 4-tuple
+    with these elements:
+
+        0. The name (a string).
+
+        1. The kind of attribute this is, one of these strings:
+               'class method'    created via classmethod()
+               'static method'   created via staticmethod()
+               'property'        created via property()
+               'method'          any other flavor of method or descriptor
+               'data'            not a method
+
+        2. The class which defined this attribute (a class).
+
+        3. The object as obtained by calling getattr; if this fails, or if the
+           resulting object does not live anywhere in the class' mro (including
+           metaclasses) then the object is looked up in the defining class's
+           dict (found by walking the mro).
+
+    If one of the items in dir(cls) is stored in the metaclass it will now
+    be discovered and not have None be listed as the class in which it was
+    defined.  Any items whose home class cannot be discovered are skipped.
+    """
+
+    mro = getmro(cls)
+    metamro = getmro(type(cls)) # for attributes stored in the metaclass
+    metamro = tuple(cls for cls in metamro if cls not in (type, object))
+    class_bases = (cls,) + mro
+    all_bases = class_bases + metamro
+    names = dir(cls)
+    # :dd any DynamicClassAttributes to the list of names;
+    # this may result in duplicate entries if, for example, a virtual
+    # attribute with the same name as a DynamicClassAttribute exists.
+    for base in mro:
+        for k, v in base.__dict__.items():
+            if isinstance(v, types.DynamicClassAttribute):
+                names.append(k)
+    result = []
+    processed = set()
+
+    for name in names:
+        # Get the object associated with the name, and where it was defined.
+        # Normal objects will be looked up with both getattr and directly in
+        # its class' dict (in case getattr fails [bug #1785], and also to look
+        # for a docstring).
+        # For DynamicClassAttributes on the second pass we only look in the
+        # class's dict.
+        #
+        # Getting an obj from the __dict__ sometimes reveals more than
+        # using getattr.  Static and class methods are dramatic examples.
+        homecls = None
+        get_obj = None
+        dict_obj = None
+        if name not in processed:
+            try:
+                if name == '__dict__':
+                    raise Exception("__dict__ is special, don't want the proxy")
+                get_obj = getattr(cls, name)
+            except Exception as exc:
+                pass
+            else:
+                homecls = getattr(get_obj, "__objclass__", homecls)
+                if homecls not in class_bases:
+                    # if the resulting object does not live somewhere in the
+                    # mro, drop it and search the mro manually
+                    homecls = None
+                    last_cls = None
+                    # first look in the classes
+                    for srch_cls in class_bases:
+                        srch_obj = getattr(srch_cls, name, None)
+                        if srch_obj is get_obj:
+                            last_cls = srch_cls
+                    # then check the metaclasses
+                    for srch_cls in metamro:
+                        try:
+                            srch_obj = srch_cls.__getattr__(cls, name)
+                        except AttributeError:
+                            continue
+                        if srch_obj is get_obj:
+                            last_cls = srch_cls
+                    if last_cls is not None:
+                        homecls = last_cls
+        for base in all_bases:
+            if name in base.__dict__:
+                dict_obj = base.__dict__[name]
+                if homecls not in metamro:
+                    homecls = base
+                break
+        if homecls is None:
+            # unable to locate the attribute anywhere, most likely due to
+            # buggy custom __dir__; discard and move on
+            continue
+        obj = get_obj if get_obj is not None else dict_obj
+        # Classify the object or its descriptor.
+        if isinstance(dict_obj, (staticmethod, types.BuiltinMethodType)):
+            kind = "static method"
+            obj = dict_obj
+        elif isinstance(dict_obj, (classmethod, types.ClassMethodDescriptorType)):
+            kind = "class method"
+            obj = dict_obj
+        elif isinstance(dict_obj, property):
+            kind = "property"
+            obj = dict_obj
+        elif isroutine(obj):
+            kind = "method"
+        else:
+            kind = "data"
+        result.append(Attribute(name, kind, homecls, obj))
+        processed.add(name)
+    return result
+
+# ----------------------------------------------------------- class helpers
+
+def getmro(cls):
+    "Return tuple of base classes (including cls) in method resolution order."
+    return cls.__mro__
+
+# -------------------------------------------------------- function helpers
+
+def unwrap(func, *, stop=None):
+    """Get the object wrapped by *func*.
+
+   Follows the chain of :attr:`__wrapped__` attributes returning the last
+   object in the chain.
+
+   *stop* is an optional callback accepting an object in the wrapper chain
+   as its sole argument that allows the unwrapping to be terminated early if
+   the callback returns a true value. If the callback never returns a true
+   value, the last object in the chain is returned as usual. For example,
+   :func:`signature` uses this to stop unwrapping if any object in the
+   chain has a ``__signature__`` attribute defined.
+
+   :exc:`ValueError` is raised if a cycle is encountered.
+
+    """
+    if stop is None:
+        def _is_wrapper(f):
+            return hasattr(f, '__wrapped__')
+    else:
+        def _is_wrapper(f):
+            return hasattr(f, '__wrapped__') and not stop(f)
+    f = func  # remember the original func for error reporting
+    # Memoise by id to tolerate non-hashable objects, but store objects to
+    # ensure they aren't destroyed, which would allow their IDs to be reused.
+    memo = {id(f): f}
+    recursion_limit = sys.getrecursionlimit()
+    while _is_wrapper(func):
+        func = func.__wrapped__
+        id_func = id(func)
+        if (id_func in memo) or (len(memo) >= recursion_limit):
+            raise ValueError('wrapper loop when unwrapping {!r}'.format(f))
+        memo[id_func] = func
+    return func
+
+# -------------------------------------------------- source code extraction
+def indentsize(line):
+    """Return the indent size, in spaces, at the start of a line of text."""
+    expline = line.expandtabs()
+    return len(expline) - len(expline.lstrip())
+
+def _findclass(func):
+    cls = sys.modules.get(func.__module__)
+    if cls is None:
+        return None
+    for name in func.__qualname__.split('.')[:-1]:
+        cls = getattr(cls, name)
+    if not isclass(cls):
+        return None
+    return cls
+
+def _finddoc(obj):
+    if isclass(obj):
+        for base in obj.__mro__:
+            if base is not object:
+                try:
+                    doc = base.__doc__
+                except AttributeError:
+                    continue
+                if doc is not None:
+                    return doc
+        return None
+
+    if ismethod(obj):
+        name = obj.__func__.__name__
+        self = obj.__self__
+        if (isclass(self) and
+            getattr(getattr(self, name, None), '__func__') is obj.__func__):
+            # classmethod
+            cls = self
+        else:
+            cls = self.__class__
+    elif isfunction(obj):
+        name = obj.__name__
+        cls = _findclass(obj)
+        if cls is None or getattr(cls, name) is not obj:
+            return None
+    elif isbuiltin(obj):
+        name = obj.__name__
+        self = obj.__self__
+        if (isclass(self) and
+            self.__qualname__ + '.' + name == obj.__qualname__):
+            # classmethod
+            cls = self
+        else:
+            cls = self.__class__
+    # Should be tested before isdatadescriptor().
+    elif isinstance(obj, property):
+        func = obj.fget
+        name = func.__name__
+        cls = _findclass(func)
+        if cls is None or getattr(cls, name) is not obj:
+            return None
+    elif ismethoddescriptor(obj) or isdatadescriptor(obj):
+        name = obj.__name__
+        cls = obj.__objclass__
+        if getattr(cls, name) is not obj:
+            return None
+        if ismemberdescriptor(obj):
+            slots = getattr(cls, '__slots__', None)
+            if isinstance(slots, dict) and name in slots:
+                return slots[name]
+    else:
+        return None
+    for base in cls.__mro__:
+        try:
+            doc = getattr(base, name).__doc__
+        except AttributeError:
+            continue
+        if doc is not None:
+            return doc
+    return None
+
+def getdoc(object):
+    """Get the documentation string for an object.
+
+    All tabs are expanded to spaces.  To clean up docstrings that are
+    indented to line up with blocks of code, any whitespace than can be
+    uniformly removed from the second line onwards is removed."""
+    try:
+        doc = object.__doc__
+    except AttributeError:
+        return None
+    if doc is None:
+        try:
+            doc = _finddoc(object)
+        except (AttributeError, TypeError):
+            return None
+    if not isinstance(doc, str):
+        return None
+    return cleandoc(doc)
+
+def cleandoc(doc):
+    """Clean up indentation from docstrings.
+
+    Any whitespace that can be uniformly removed from the second line
+    onwards is removed."""
+    try:
+        lines = doc.expandtabs().split('\n')
+    except UnicodeError:
+        return None
+    else:
+        # Find minimum indentation of any non-blank lines after first line.
+        margin = sys.maxsize
+        for line in lines[1:]:
+            content = len(line.lstrip())
+            if content:
+                indent = len(line) - content
+                margin = min(margin, indent)
+        # Remove indentation.
+        if lines:
+            lines[0] = lines[0].lstrip()
+        if margin < sys.maxsize:
+            for i in range(1, len(lines)): lines[i] = lines[i][margin:]
+        # Remove any trailing or leading blank lines.
+        while lines and not lines[-1]:
+            lines.pop()
+        while lines and not lines[0]:
+            lines.pop(0)
+        return '\n'.join(lines)
+
+def getfile(object):
+    """Work out which source or compiled file an object was defined in."""
+    if ismodule(object):
+        if getattr(object, '__file__', None):
+            return object.__file__
+        raise TypeError('{!r} is a built-in module'.format(object))
+    if isclass(object):
+        if hasattr(object, '__module__'):
+            module = sys.modules.get(object.__module__)
+            if getattr(module, '__file__', None):
+                return module.__file__
+        raise TypeError('{!r} is a built-in class'.format(object))
+    if ismethod(object):
+        object = object.__func__
+    if isfunction(object):
+        object = object.__code__
+    if istraceback(object):
+        object = object.tb_frame
+    if isframe(object):
+        object = object.f_code
+    if iscode(object):
+        return object.co_filename
+    raise TypeError('module, class, method, function, traceback, frame, or '
+                    'code object was expected, got {}'.format(
+                    type(object).__name__))
+
+def getmodulename(path):
+    """Return the module name for a given file, or None."""
+    fname = os.path.basename(path)
+    # Check for paths that look like an actual module file
+    suffixes = [(-len(suffix), suffix)
+                    for suffix in importlib.machinery.all_suffixes()]
+    suffixes.sort() # try longest suffixes first, in case they overlap
+    for neglen, suffix in suffixes:
+        if fname.endswith(suffix):
+            return fname[:neglen]
+    return None
+
+def getsourcefile(object):
+    """Return the filename that can be used to locate an object's source.
+    Return None if no way can be identified to get the source.
+    """
+    filename = getfile(object)
+    all_bytecode_suffixes = importlib.machinery.DEBUG_BYTECODE_SUFFIXES[:]
+    all_bytecode_suffixes += importlib.machinery.OPTIMIZED_BYTECODE_SUFFIXES[:]
+    if any(filename.endswith(s) for s in all_bytecode_suffixes):
+        filename = (os.path.splitext(filename)[0] +
+                    importlib.machinery.SOURCE_SUFFIXES[0])
+    elif any(filename.endswith(s) for s in
+                 importlib.machinery.EXTENSION_SUFFIXES):
+        return None
+    if os.path.exists(filename):
+        return filename
+    # only return a non-existent filename if the module has a PEP 302 loader
+    if getattr(getmodule(object, filename), '__loader__', None) is not None:
+        return filename
+    # or it is in the linecache
+    if filename in linecache.cache:
+        return filename
+
+def getabsfile(object, _filename=None):
+    """Return an absolute path to the source or compiled file for an object.
+
+    The idea is for each object to have a unique origin, so this routine
+    normalizes the result as much as possible."""
+    if _filename is None:
+        _filename = getsourcefile(object) or getfile(object)
+    return os.path.normcase(os.path.abspath(_filename))
+
+modulesbyfile = {}
+_filesbymodname = {}
+
+def getmodule(object, _filename=None):
+    """Return the module an object was defined in, or None if not found."""
+    if ismodule(object):
+        return object
+    if hasattr(object, '__module__'):
+        return sys.modules.get(object.__module__)
+    # Try the filename to modulename cache
+    if _filename is not None and _filename in modulesbyfile:
+        return sys.modules.get(modulesbyfile[_filename])
+    # Try the cache again with the absolute file name
+    try:
+        file = getabsfile(object, _filename)
+    except TypeError:
+        return None
+    if file in modulesbyfile:
+        return sys.modules.get(modulesbyfile[file])
+    # Update the filename to module name cache and check yet again
+    # Copy sys.modules in order to cope with changes while iterating
+    for modname, module in sys.modules.copy().items():
+        if ismodule(module) and hasattr(module, '__file__'):
+            f = module.__file__
+            if f == _filesbymodname.get(modname, None):
+                # Have already mapped this module, so skip it
+                continue
+            _filesbymodname[modname] = f
+            f = getabsfile(module)
+            # Always map to the name the module knows itself by
+            modulesbyfile[f] = modulesbyfile[
+                os.path.realpath(f)] = module.__name__
+    if file in modulesbyfile:
+        return sys.modules.get(modulesbyfile[file])
+    # Check the main module
+    main = sys.modules['__main__']
+    if not hasattr(object, '__name__'):
+        return None
+    if hasattr(main, object.__name__):
+        mainobject = getattr(main, object.__name__)
+        if mainobject is object:
+            return main
+    # Check builtins
+    builtin = sys.modules['builtins']
+    if hasattr(builtin, object.__name__):
+        builtinobject = getattr(builtin, object.__name__)
+        if builtinobject is object:
+            return builtin
+
+
+class ClassFoundException(Exception):
+    pass
+
+
+class _ClassFinder(ast.NodeVisitor):
+
+    def __init__(self, qualname):
+        self.stack = []
+        self.qualname = qualname
+
+    def visit_FunctionDef(self, node):
+        self.stack.append(node.name)
+        self.stack.append('<locals>')
+        self.generic_visit(node)
+        self.stack.pop()
+        self.stack.pop()
+
+    visit_AsyncFunctionDef = visit_FunctionDef
+
+    def visit_ClassDef(self, node):
+        self.stack.append(node.name)
+        if self.qualname == '.'.join(self.stack):
+            # Return the decorator for the class if present
+            if node.decorator_list:
+                line_number = node.decorator_list[0].lineno
+            else:
+                line_number = node.lineno
+
+            # decrement by one since lines starts with indexing by zero
+            line_number -= 1
+            raise ClassFoundException(line_number)
+        self.generic_visit(node)
+        self.stack.pop()
+
+
+def findsource(object):
+    """Return the entire source file and starting line number for an object.
+
+    The argument may be a module, class, method, function, traceback, frame,
+    or code object.  The source code is returned as a list of all the lines
+    in the file and the line number indexes a line in that list.  An OSError
+    is raised if the source code cannot be retrieved."""
+
+    file = getsourcefile(object)
+    if file:
+        # Invalidate cache if needed.
+        linecache.checkcache(file)
+    else:
+        file = getfile(object)
+        # Allow filenames in form of "<something>" to pass through.
+        # `doctest` monkeypatches `linecache` module to enable
+        # inspection, so let `linecache.getlines` to be called.
+        if not (file.startswith('<') and file.endswith('>')):
+            raise OSError('source code not available')
+
+    module = getmodule(object, file)
+    if module:
+        lines = linecache.getlines(file, module.__dict__)
+    else:
+        lines = linecache.getlines(file)
+    if not lines:
+        raise OSError('could not get source code')
+
+    if ismodule(object):
+        return lines, 0
+
+    if isclass(object):
+        qualname = object.__qualname__
+        source = ''.join(lines)
+        tree = ast.parse(source)
+        class_finder = _ClassFinder(qualname)
+        try:
+            class_finder.visit(tree)
+        except ClassFoundException as e:
+            line_number = e.args[0]
+            return lines, line_number
+        else:
+            raise OSError('could not find class definition')
+
+    if ismethod(object):
+        object = object.__func__
+    if isfunction(object):
+        object = object.__code__
+    if istraceback(object):
+        object = object.tb_frame
+    if isframe(object):
+        object = object.f_code
+    if iscode(object):
+        if not hasattr(object, 'co_firstlineno'):
+            raise OSError('could not find function definition')
+        lnum = object.co_firstlineno - 1
+        pat = re.compile(r'^(\s*def\s)|(\s*async\s+def\s)|(.*(?<!\w)lambda(:|\s))|^(\s*@)')
+        while lnum > 0:
+            try:
+                line = lines[lnum]
+            except IndexError:
+                raise OSError('lineno is out of bounds')
+            if pat.match(line):
+                break
+            lnum = lnum - 1
+        return lines, lnum
+    raise OSError('could not find code object')
+
+def getcomments(object):
+    """Get lines of comments immediately preceding an object's source code.
+
+    Returns None when source can't be found.
+    """
+    try:
+        lines, lnum = findsource(object)
+    except (OSError, TypeError):
+        return None
+
+    if ismodule(object):
+        # Look for a comment block at the top of the file.
+        start = 0
+        if lines and lines[0][:2] == '#!': start = 1
+        while start < len(lines) and lines[start].strip() in ('', '#'):
+            start = start + 1
+        if start < len(lines) and lines[start][:1] == '#':
+            comments = []
+            end = start
+            while end < len(lines) and lines[end][:1] == '#':
+                comments.append(lines[end].expandtabs())
+                end = end + 1
+            return ''.join(comments)
+
+    # Look for a preceding block of comments at the same indentation.
+    elif lnum > 0:
+        indent = indentsize(lines[lnum])
+        end = lnum - 1
+        if end >= 0 and lines[end].lstrip()[:1] == '#' and \
+            indentsize(lines[end]) == indent:
+            comments = [lines[end].expandtabs().lstrip()]
+            if end > 0:
+                end = end - 1
+                comment = lines[end].expandtabs().lstrip()
+                while comment[:1] == '#' and indentsize(lines[end]) == indent:
+                    comments[:0] = [comment]
+                    end = end - 1
+                    if end < 0: break
+                    comment = lines[end].expandtabs().lstrip()
+            while comments and comments[0].strip() == '#':
+                comments[:1] = []
+            while comments and comments[-1].strip() == '#':
+                comments[-1:] = []
+            return ''.join(comments)
+
+class EndOfBlock(Exception): pass
+
+class BlockFinder:
+    """Provide a tokeneater() method to detect the end of a code block."""
+    def __init__(self):
+        self.indent = 0
+        self.islambda = False
+        self.started = False
+        self.passline = False
+        self.indecorator = False
+        self.decoratorhasargs = False
+        self.last = 1
+        self.body_col0 = None
+
+    def tokeneater(self, type, token, srowcol, erowcol, line):
+        if not self.started and not self.indecorator:
+            # skip any decorators
+            if token == "@":
+                self.indecorator = True
+            # look for the first "def", "class" or "lambda"
+            elif token in ("def", "class", "lambda"):
+                if token == "lambda":
+                    self.islambda = True
+                self.started = True
+            self.passline = True    # skip to the end of the line
+        elif token == "(":
+            if self.indecorator:
+                self.decoratorhasargs = True
+        elif token == ")":
+            if self.indecorator:
+                self.indecorator = False
+                self.decoratorhasargs = False
+        elif type == tokenize.NEWLINE:
+            self.passline = False   # stop skipping when a NEWLINE is seen
+            self.last = srowcol[0]
+            if self.islambda:       # lambdas always end at the first NEWLINE
+                raise EndOfBlock
+            # hitting a NEWLINE when in a decorator without args
+            # ends the decorator
+            if self.indecorator and not self.decoratorhasargs:
+                self.indecorator = False
+        elif self.passline:
+            pass
+        elif type == tokenize.INDENT:
+            if self.body_col0 is None and self.started:
+                self.body_col0 = erowcol[1]
+            self.indent = self.indent + 1
+            self.passline = True
+        elif type == tokenize.DEDENT:
+            self.indent = self.indent - 1
+            # the end of matching indent/dedent pairs end a block
+            # (note that this only works for "def"/"class" blocks,
+            #  not e.g. for "if: else:" or "try: finally:" blocks)
+            if self.indent <= 0:
+                raise EndOfBlock
+        elif type == tokenize.COMMENT:
+            if self.body_col0 is not None and srowcol[1] >= self.body_col0:
+                # Include comments if indented at least as much as the block
+                self.last = srowcol[0]
+        elif self.indent == 0 and type not in (tokenize.COMMENT, tokenize.NL):
+            # any other token on the same indentation level end the previous
+            # block as well, except the pseudo-tokens COMMENT and NL.
+            raise EndOfBlock
+
+def getblock(lines):
+    """Extract the block of code at the top of the given list of lines."""
+    blockfinder = BlockFinder()
+    try:
+        tokens = tokenize.generate_tokens(iter(lines).__next__)
+        for _token in tokens:
+            blockfinder.tokeneater(*_token)
+    except (EndOfBlock, IndentationError):
+        pass
+    return lines[:blockfinder.last]
+
+def getsourcelines(object):
+    """Return a list of source lines and starting line number for an object.
+
+    The argument may be a module, class, method, function, traceback, frame,
+    or code object.  The source code is returned as a list of the lines
+    corresponding to the object and the line number indicates where in the
+    original source file the first line of code was found.  An OSError is
+    raised if the source code cannot be retrieved."""
+    object = unwrap(object)
+    lines, lnum = findsource(object)
+
+    if istraceback(object):
+        object = object.tb_frame
+
+    # for module or frame that corresponds to module, return all source lines
+    if (ismodule(object) or
+        (isframe(object) and object.f_code.co_name == "<module>")):
+        return lines, 0
+    else:
+        return getblock(lines[lnum:]), lnum + 1
+
+def getsource(object):
+    """Return the text of the source code for an object.
+
+    The argument may be a module, class, method, function, traceback, frame,
+    or code object.  The source code is returned as a single string.  An
+    OSError is raised if the source code cannot be retrieved."""
+    lines, lnum = getsourcelines(object)
+    return ''.join(lines)
+
+# --------------------------------------------------- class tree extraction
+def walktree(classes, children, parent):
+    """Recursive helper function for getclasstree()."""
+    results = []
+    classes.sort(key=attrgetter('__module__', '__name__'))
+    for c in classes:
+        results.append((c, c.__bases__))
+        if c in children:
+            results.append(walktree(children[c], children, c))
+    return results
+
+def getclasstree(classes, unique=False):
+    """Arrange the given list of classes into a hierarchy of nested lists.
+
+    Where a nested list appears, it contains classes derived from the class
+    whose entry immediately precedes the list.  Each entry is a 2-tuple
+    containing a class and a tuple of its base classes.  If the 'unique'
+    argument is true, exactly one entry appears in the returned structure
+    for each class in the given list.  Otherwise, classes using multiple
+    inheritance and their descendants will appear multiple times."""
+    children = {}
+    roots = []
+    for c in classes:
+        if c.__bases__:
+            for parent in c.__bases__:
+                if parent not in children:
+                    children[parent] = []
+                if c not in children[parent]:
+                    children[parent].append(c)
+                if unique and parent in classes: break
+        elif c not in roots:
+            roots.append(c)
+    for parent in children:
+        if parent not in classes:
+            roots.append(parent)
+    return walktree(roots, children, None)
+
+# ------------------------------------------------ argument list extraction
+Arguments = namedtuple('Arguments', 'args, varargs, varkw')
+
+def getargs(co):
+    """Get information about the arguments accepted by a code object.
+
+    Three things are returned: (args, varargs, varkw), where
+    'args' is the list of argument names. Keyword-only arguments are
+    appended. 'varargs' and 'varkw' are the names of the * and **
+    arguments or None."""
+    if not iscode(co):
+        raise TypeError('{!r} is not a code object'.format(co))
+
+    names = co.co_varnames
+    nargs = co.co_argcount
+    nkwargs = co.co_kwonlyargcount
+    args = list(names[:nargs])
+    kwonlyargs = list(names[nargs:nargs+nkwargs])
+    step = 0
+
+    nargs += nkwargs
+    varargs = None
+    if co.co_flags & CO_VARARGS:
+        varargs = co.co_varnames[nargs]
+        nargs = nargs + 1
+    varkw = None
+    if co.co_flags & CO_VARKEYWORDS:
+        varkw = co.co_varnames[nargs]
+    return Arguments(args + kwonlyargs, varargs, varkw)
+
+ArgSpec = namedtuple('ArgSpec', 'args varargs keywords defaults')
+
+def getargspec(func):
+    """Get the names and default values of a function's parameters.
+
+    A tuple of four things is returned: (args, varargs, keywords, defaults).
+    'args' is a list of the argument names, including keyword-only argument names.
+    'varargs' and 'keywords' are the names of the * and ** parameters or None.
+    'defaults' is an n-tuple of the default values of the last n parameters.
+
+    This function is deprecated, as it does not support annotations or
+    keyword-only parameters and will raise ValueError if either is present
+    on the supplied callable.
+
+    For a more structured introspection API, use inspect.signature() instead.
+
+    Alternatively, use getfullargspec() for an API with a similar namedtuple
+    based interface, but full support for annotations and keyword-only
+    parameters.
+
+    Deprecated since Python 3.5, use `inspect.getfullargspec()`.
+    """
+    warnings.warn("inspect.getargspec() is deprecated since Python 3.0, "
+                  "use inspect.signature() or inspect.getfullargspec()",
+                  DeprecationWarning, stacklevel=2)
+    args, varargs, varkw, defaults, kwonlyargs, kwonlydefaults, ann = \
+        getfullargspec(func)
+    if kwonlyargs or ann:
+        raise ValueError("Function has keyword-only parameters or annotations"
+                         ", use inspect.signature() API which can support them")
+    return ArgSpec(args, varargs, varkw, defaults)
+
+FullArgSpec = namedtuple('FullArgSpec',
+    'args, varargs, varkw, defaults, kwonlyargs, kwonlydefaults, annotations')
+
+def getfullargspec(func):
+    """Get the names and default values of a callable object's parameters.
+
+    A tuple of seven things is returned:
+    (args, varargs, varkw, defaults, kwonlyargs, kwonlydefaults, annotations).
+    'args' is a list of the parameter names.
+    'varargs' and 'varkw' are the names of the * and ** parameters or None.
+    'defaults' is an n-tuple of the default values of the last n parameters.
+    'kwonlyargs' is a list of keyword-only parameter names.
+    'kwonlydefaults' is a dictionary mapping names from kwonlyargs to defaults.
+    'annotations' is a dictionary mapping parameter names to annotations.
+
+    Notable differences from inspect.signature():
+      - the "self" parameter is always reported, even for bound methods
+      - wrapper chains defined by __wrapped__ *not* unwrapped automatically
+    """
+    try:
+        # Re: `skip_bound_arg=False`
+        #
+        # There is a notable difference in behaviour between getfullargspec
+        # and Signature: the former always returns 'self' parameter for bound
+        # methods, whereas the Signature always shows the actual calling
+        # signature of the passed object.
+        #
+        # To simulate this behaviour, we "unbind" bound methods, to trick
+        # inspect.signature to always return their first parameter ("self",
+        # usually)
+
+        # Re: `follow_wrapper_chains=False`
+        #
+        # getfullargspec() historically ignored __wrapped__ attributes,
+        # so we ensure that remains the case in 3.3+
+
+        sig = _signature_from_callable(func,
+                                       follow_wrapper_chains=False,
+                                       skip_bound_arg=False,
+                                       sigcls=Signature)
+    except Exception as ex:
+        # Most of the times 'signature' will raise ValueError.
+        # But, it can also raise AttributeError, and, maybe something
+        # else. So to be fully backwards compatible, we catch all
+        # possible exceptions here, and reraise a TypeError.
+        raise TypeError('unsupported callable') from ex
+
+    args = []
+    varargs = None
+    varkw = None
+    posonlyargs = []
+    kwonlyargs = []
+    annotations = {}
+    defaults = ()
+    kwdefaults = {}
+
+    if sig.return_annotation is not sig.empty:
+        annotations['return'] = sig.return_annotation
+
+    for param in sig.parameters.values():
+        kind = param.kind
+        name = param.name
+
+        if kind is _POSITIONAL_ONLY:
+            posonlyargs.append(name)
+            if param.default is not param.empty:
+                defaults += (param.default,)
+        elif kind is _POSITIONAL_OR_KEYWORD:
+            args.append(name)
+            if param.default is not param.empty:
+                defaults += (param.default,)
+        elif kind is _VAR_POSITIONAL:
+            varargs = name
+        elif kind is _KEYWORD_ONLY:
+            kwonlyargs.append(name)
+            if param.default is not param.empty:
+                kwdefaults[name] = param.default
+        elif kind is _VAR_KEYWORD:
+            varkw = name
+
+        if param.annotation is not param.empty:
+            annotations[name] = param.annotation
+
+    if not kwdefaults:
+        # compatibility with 'func.__kwdefaults__'
+        kwdefaults = None
+
+    if not defaults:
+        # compatibility with 'func.__defaults__'
+        defaults = None
+
+    return FullArgSpec(posonlyargs + args, varargs, varkw, defaults,
+                       kwonlyargs, kwdefaults, annotations)
+
+
+ArgInfo = namedtuple('ArgInfo', 'args varargs keywords locals')
+
+def getargvalues(frame):
+    """Get information about arguments passed into a particular frame.
+
+    A tuple of four things is returned: (args, varargs, varkw, locals).
+    'args' is a list of the argument names.
+    'varargs' and 'varkw' are the names of the * and ** arguments or None.
+    'locals' is the locals dictionary of the given frame."""
+    args, varargs, varkw = getargs(frame.f_code)
+    return ArgInfo(args, varargs, varkw, frame.f_locals)
+
+def formatannotation(annotation, base_module=None):
+    if getattr(annotation, '__module__', None) == 'typing':
+        return repr(annotation).replace('typing.', '')
+    if isinstance(annotation, type):
+        if annotation.__module__ in ('builtins', base_module):
+            return annotation.__qualname__
+        return annotation.__module__+'.'+annotation.__qualname__
+    return repr(annotation)
+
+def formatannotationrelativeto(object):
+    module = getattr(object, '__module__', None)
+    def _formatannotation(annotation):
+        return formatannotation(annotation, module)
+    return _formatannotation
+
+def formatargspec(args, varargs=None, varkw=None, defaults=None,
+                  kwonlyargs=(), kwonlydefaults={}, annotations={},
+                  formatarg=str,
+                  formatvarargs=lambda name: '*' + name,
+                  formatvarkw=lambda name: '**' + name,
+                  formatvalue=lambda value: '=' + repr(value),
+                  formatreturns=lambda text: ' -> ' + text,
+                  formatannotation=formatannotation):
+    """Format an argument spec from the values returned by getfullargspec.
+
+    The first seven arguments are (args, varargs, varkw, defaults,
+    kwonlyargs, kwonlydefaults, annotations).  The other five arguments
+    are the corresponding optional formatting functions that are called to
+    turn names and values into strings.  The last argument is an optional
+    function to format the sequence of arguments.
+
+    Deprecated since Python 3.5: use the `signature` function and `Signature`
+    objects.
+    """
+
+    from warnings import warn
+
+    warn("`formatargspec` is deprecated since Python 3.5. Use `signature` and "
+         "the `Signature` object directly",
+         DeprecationWarning,
+         stacklevel=2)
+
+    def formatargandannotation(arg):
+        result = formatarg(arg)
+        if arg in annotations:
+            result += ': ' + formatannotation(annotations[arg])
+        return result
+    specs = []
+    if defaults:
+        firstdefault = len(args) - len(defaults)
+    for i, arg in enumerate(args):
+        spec = formatargandannotation(arg)
+        if defaults and i >= firstdefault:
+            spec = spec + formatvalue(defaults[i - firstdefault])
+        specs.append(spec)
+    if varargs is not None:
+        specs.append(formatvarargs(formatargandannotation(varargs)))
+    else:
+        if kwonlyargs:
+            specs.append('*')
+    if kwonlyargs:
+        for kwonlyarg in kwonlyargs:
+            spec = formatargandannotation(kwonlyarg)
+            if kwonlydefaults and kwonlyarg in kwonlydefaults:
+                spec += formatvalue(kwonlydefaults[kwonlyarg])
+            specs.append(spec)
+    if varkw is not None:
+        specs.append(formatvarkw(formatargandannotation(varkw)))
+    result = '(' + ', '.join(specs) + ')'
+    if 'return' in annotations:
+        result += formatreturns(formatannotation(annotations['return']))
+    return result
+
+def formatargvalues(args, varargs, varkw, locals,
+                    formatarg=str,
+                    formatvarargs=lambda name: '*' + name,
+                    formatvarkw=lambda name: '**' + name,
+                    formatvalue=lambda value: '=' + repr(value)):
+    """Format an argument spec from the 4 values returned by getargvalues.
+
+    The first four arguments are (args, varargs, varkw, locals).  The
+    next four arguments are the corresponding optional formatting functions
+    that are called to turn names and values into strings.  The ninth
+    argument is an optional function to format the sequence of arguments."""
+    def convert(name, locals=locals,
+                formatarg=formatarg, formatvalue=formatvalue):
+        return formatarg(name) + formatvalue(locals[name])
+    specs = []
+    for i in range(len(args)):
+        specs.append(convert(args[i]))
+    if varargs:
+        specs.append(formatvarargs(varargs) + formatvalue(locals[varargs]))
+    if varkw:
+        specs.append(formatvarkw(varkw) + formatvalue(locals[varkw]))
+    return '(' + ', '.join(specs) + ')'
+
+def _missing_arguments(f_name, argnames, pos, values):
+    names = [repr(name) for name in argnames if name not in values]
+    missing = len(names)
+    if missing == 1:
+        s = names[0]
+    elif missing == 2:
+        s = "{} and {}".format(*names)
+    else:
+        tail = ", {} and {}".format(*names[-2:])
+        del names[-2:]
+        s = ", ".join(names) + tail
+    raise TypeError("%s() missing %i required %s argument%s: %s" %
+                    (f_name, missing,
+                      "positional" if pos else "keyword-only",
+                      "" if missing == 1 else "s", s))
+
+def _too_many(f_name, args, kwonly, varargs, defcount, given, values):
+    atleast = len(args) - defcount
+    kwonly_given = len([arg for arg in kwonly if arg in values])
+    if varargs:
+        plural = atleast != 1
+        sig = "at least %d" % (atleast,)
+    elif defcount:
+        plural = True
+        sig = "from %d to %d" % (atleast, len(args))
+    else:
+        plural = len(args) != 1
+        sig = str(len(args))
+    kwonly_sig = ""
+    if kwonly_given:
+        msg = " positional argument%s (and %d keyword-only argument%s)"
+        kwonly_sig = (msg % ("s" if given != 1 else "", kwonly_given,
+                             "s" if kwonly_given != 1 else ""))
+    raise TypeError("%s() takes %s positional argument%s but %d%s %s given" %
+            (f_name, sig, "s" if plural else "", given, kwonly_sig,
+             "was" if given == 1 and not kwonly_given else "were"))
+
+def getcallargs(func, /, *positional, **named):
+    """Get the mapping of arguments to values.
+
+    A dict is returned, with keys the function argument names (including the
+    names of the * and ** arguments, if any), and values the respective bound
+    values from 'positional' and 'named'."""
+    spec = getfullargspec(func)
+    args, varargs, varkw, defaults, kwonlyargs, kwonlydefaults, ann = spec
+    f_name = func.__name__
+    arg2value = {}
+
+
+    if ismethod(func) and func.__self__ is not None:
+        # implicit 'self' (or 'cls' for classmethods) argument
+        positional = (func.__self__,) + positional
+    num_pos = len(positional)
+    num_args = len(args)
+    num_defaults = len(defaults) if defaults else 0
+
+    n = min(num_pos, num_args)
+    for i in range(n):
+        arg2value[args[i]] = positional[i]
+    if varargs:
+        arg2value[varargs] = tuple(positional[n:])
+    possible_kwargs = set(args + kwonlyargs)
+    if varkw:
+        arg2value[varkw] = {}
+    for kw, value in named.items():
+        if kw not in possible_kwargs:
+            if not varkw:
+                raise TypeError("%s() got an unexpected keyword argument %r" %
+                                (f_name, kw))
+            arg2value[varkw][kw] = value
+            continue
+        if kw in arg2value:
+            raise TypeError("%s() got multiple values for argument %r" %
+                            (f_name, kw))
+        arg2value[kw] = value
+    if num_pos > num_args and not varargs:
+        _too_many(f_name, args, kwonlyargs, varargs, num_defaults,
+                   num_pos, arg2value)
+    if num_pos < num_args:
+        req = args[:num_args - num_defaults]
+        for arg in req:
+            if arg not in arg2value:
+                _missing_arguments(f_name, req, True, arg2value)
+        for i, arg in enumerate(args[num_args - num_defaults:]):
+            if arg not in arg2value:
+                arg2value[arg] = defaults[i]
+    missing = 0
+    for kwarg in kwonlyargs:
+        if kwarg not in arg2value:
+            if kwonlydefaults and kwarg in kwonlydefaults:
+                arg2value[kwarg] = kwonlydefaults[kwarg]
+            else:
+                missing += 1
+    if missing:
+        _missing_arguments(f_name, kwonlyargs, False, arg2value)
+    return arg2value
+
+ClosureVars = namedtuple('ClosureVars', 'nonlocals globals builtins unbound')
+
+def getclosurevars(func):
+    """
+    Get the mapping of free variables to their current values.
+
+    Returns a named tuple of dicts mapping the current nonlocal, global
+    and builtin references as seen by the body of the function. A final
+    set of unbound names that could not be resolved is also provided.
+    """
+
+    if ismethod(func):
+        func = func.__func__
+
+    if not isfunction(func):
+        raise TypeError("{!r} is not a Python function".format(func))
+
+    code = func.__code__
+    # Nonlocal references are named in co_freevars and resolved
+    # by looking them up in __closure__ by positional index
+    if func.__closure__ is None:
+        nonlocal_vars = {}
+    else:
+        nonlocal_vars = {
+            var : cell.cell_contents
+            for var, cell in zip(code.co_freevars, func.__closure__)
+       }
+
+    # Global and builtin references are named in co_names and resolved
+    # by looking them up in __globals__ or __builtins__
+    global_ns = func.__globals__
+    builtin_ns = global_ns.get("__builtins__", builtins.__dict__)
+    if ismodule(builtin_ns):
+        builtin_ns = builtin_ns.__dict__
+    global_vars = {}
+    builtin_vars = {}
+    unbound_names = set()
+    for name in code.co_names:
+        if name in ("None", "True", "False"):
+            # Because these used to be builtins instead of keywords, they
+            # may still show up as name references. We ignore them.
+            continue
+        try:
+            global_vars[name] = global_ns[name]
+        except KeyError:
+            try:
+                builtin_vars[name] = builtin_ns[name]
+            except KeyError:
+                unbound_names.add(name)
+
+    return ClosureVars(nonlocal_vars, global_vars,
+                       builtin_vars, unbound_names)
+
+# -------------------------------------------------- stack frame extraction
+
+Traceback = namedtuple('Traceback', 'filename lineno function code_context index')
+
+def getframeinfo(frame, context=1):
+    """Get information about a frame or traceback object.
+
+    A tuple of five things is returned: the filename, the line number of
+    the current line, the function name, a list of lines of context from
+    the source code, and the index of the current line within that list.
+    The optional second argument specifies the number of lines of context
+    to return, which are centered around the current line."""
+    if istraceback(frame):
+        lineno = frame.tb_lineno
+        frame = frame.tb_frame
+    else:
+        lineno = frame.f_lineno
+    if not isframe(frame):
+        raise TypeError('{!r} is not a frame or traceback object'.format(frame))
+
+    filename = getsourcefile(frame) or getfile(frame)
+    if context > 0:
+        start = lineno - 1 - context//2
+        try:
+            lines, lnum = findsource(frame)
+        except OSError:
+            lines = index = None
+        else:
+            start = max(0, min(start, len(lines) - context))
+            lines = lines[start:start+context]
+            index = lineno - 1 - start
+    else:
+        lines = index = None
+
+    return Traceback(filename, lineno, frame.f_code.co_name, lines, index)
+
+def getlineno(frame):
+    """Get the line number from a frame object, allowing for optimization."""
+    # FrameType.f_lineno is now a descriptor that grovels co_lnotab
+    return frame.f_lineno
+
+FrameInfo = namedtuple('FrameInfo', ('frame',) + Traceback._fields)
+
+def getouterframes(frame, context=1):
+    """Get a list of records for a frame and all higher (calling) frames.
+
+    Each record contains a frame object, filename, line number, function
+    name, a list of lines of context, and index within the context."""
+    framelist = []
+    while frame:
+        frameinfo = (frame,) + getframeinfo(frame, context)
+        framelist.append(FrameInfo(*frameinfo))
+        frame = frame.f_back
+    return framelist
+
+def getinnerframes(tb, context=1):
+    """Get a list of records for a traceback's frame and all lower frames.
+
+    Each record contains a frame object, filename, line number, function
+    name, a list of lines of context, and index within the context."""
+    framelist = []
+    while tb:
+        frameinfo = (tb.tb_frame,) + getframeinfo(tb, context)
+        framelist.append(FrameInfo(*frameinfo))
+        tb = tb.tb_next
+    return framelist
+
+def currentframe():
+    """Return the frame of the caller or None if this is not possible."""
+    return sys._getframe(1) if hasattr(sys, "_getframe") else None
+
+def stack(context=1):
+    """Return a list of records for the stack above the caller's frame."""
+    return getouterframes(sys._getframe(1), context)
+
+def trace(context=1):
+    """Return a list of records for the stack below the current exception."""
+    return getinnerframes(sys.exc_info()[2], context)
+
+
+# ------------------------------------------------ static version of getattr
+
+_sentinel = object()
+
+def _static_getmro(klass):
+    return type.__dict__['__mro__'].__get__(klass)
+
+def _check_instance(obj, attr):
+    instance_dict = {}
+    try:
+        instance_dict = object.__getattribute__(obj, "__dict__")
+    except AttributeError:
+        pass
+    return dict.get(instance_dict, attr, _sentinel)
+
+
+def _check_class(klass, attr):
+    for entry in _static_getmro(klass):
+        if _shadowed_dict(type(entry)) is _sentinel:
+            try:
+                return entry.__dict__[attr]
+            except KeyError:
+                pass
+    return _sentinel
+
+def _is_type(obj):
+    try:
+        _static_getmro(obj)
+    except TypeError:
+        return False
+    return True
+
+def _shadowed_dict(klass):
+    dict_attr = type.__dict__["__dict__"]
+    for entry in _static_getmro(klass):
+        try:
+            class_dict = dict_attr.__get__(entry)["__dict__"]
+        except KeyError:
+            pass
+        else:
+            if not (type(class_dict) is types.GetSetDescriptorType and
+                    class_dict.__name__ == "__dict__" and
+                    class_dict.__objclass__ is entry):
+                return class_dict
+    return _sentinel
+
+def getattr_static(obj, attr, default=_sentinel):
+    """Retrieve attributes without triggering dynamic lookup via the
+       descriptor protocol,  __getattr__ or __getattribute__.
+
+       Note: this function may not be able to retrieve all attributes
+       that getattr can fetch (like dynamically created attributes)
+       and may find attributes that getattr can't (like descriptors
+       that raise AttributeError). It can also return descriptor objects
+       instead of instance members in some cases. See the
+       documentation for details.
+    """
+    instance_result = _sentinel
+    if not _is_type(obj):
+        klass = type(obj)
+        dict_attr = _shadowed_dict(klass)
+        if (dict_attr is _sentinel or
+            type(dict_attr) is types.MemberDescriptorType):
+            instance_result = _check_instance(obj, attr)
+    else:
+        klass = obj
+
+    klass_result = _check_class(klass, attr)
+
+    if instance_result is not _sentinel and klass_result is not _sentinel:
+        if (_check_class(type(klass_result), '__get__') is not _sentinel and
+            _check_class(type(klass_result), '__set__') is not _sentinel):
+            return klass_result
+
+    if instance_result is not _sentinel:
+        return instance_result
+    if klass_result is not _sentinel:
+        return klass_result
+
+    if obj is klass:
+        # for types we check the metaclass too
+        for entry in _static_getmro(type(klass)):
+            if _shadowed_dict(type(entry)) is _sentinel:
+                try:
+                    return entry.__dict__[attr]
+                except KeyError:
+                    pass
+    if default is not _sentinel:
+        return default
+    raise AttributeError(attr)
+
+
+# ------------------------------------------------ generator introspection
+
+GEN_CREATED = 'GEN_CREATED'
+GEN_RUNNING = 'GEN_RUNNING'
+GEN_SUSPENDED = 'GEN_SUSPENDED'
+GEN_CLOSED = 'GEN_CLOSED'
+
+def getgeneratorstate(generator):
+    """Get current state of a generator-iterator.
+
+    Possible states are:
+      GEN_CREATED: Waiting to start execution.
+      GEN_RUNNING: Currently being executed by the interpreter.
+      GEN_SUSPENDED: Currently suspended at a yield expression.
+      GEN_CLOSED: Execution has completed.
+    """
+    if generator.gi_running:
+        return GEN_RUNNING
+    if generator.gi_frame is None:
+        return GEN_CLOSED
+    if generator.gi_frame.f_lasti == -1:
+        return GEN_CREATED
+    return GEN_SUSPENDED
+
+
+def getgeneratorlocals(generator):
+    """
+    Get the mapping of generator local variables to their current values.
+
+    A dict is returned, with the keys the local variable names and values the
+    bound values."""
+
+    if not isgenerator(generator):
+        raise TypeError("{!r} is not a Python generator".format(generator))
+
+    frame = getattr(generator, "gi_frame", None)
+    if frame is not None:
+        return generator.gi_frame.f_locals
+    else:
+        return {}
+
+
+# ------------------------------------------------ coroutine introspection
+
+CORO_CREATED = 'CORO_CREATED'
+CORO_RUNNING = 'CORO_RUNNING'
+CORO_SUSPENDED = 'CORO_SUSPENDED'
+CORO_CLOSED = 'CORO_CLOSED'
+
+def getcoroutinestate(coroutine):
+    """Get current state of a coroutine object.
+
+    Possible states are:
+      CORO_CREATED: Waiting to start execution.
+      CORO_RUNNING: Currently being executed by the interpreter.
+      CORO_SUSPENDED: Currently suspended at an await expression.
+      CORO_CLOSED: Execution has completed.
+    """
+    if coroutine.cr_running:
+        return CORO_RUNNING
+    if coroutine.cr_frame is None:
+        return CORO_CLOSED
+    if coroutine.cr_frame.f_lasti == -1:
+        return CORO_CREATED
+    return CORO_SUSPENDED
+
+
+def getcoroutinelocals(coroutine):
+    """
+    Get the mapping of coroutine local variables to their current values.
+
+    A dict is returned, with the keys the local variable names and values the
+    bound values."""
+    frame = getattr(coroutine, "cr_frame", None)
+    if frame is not None:
+        return frame.f_locals
+    else:
+        return {}
+
+
+###############################################################################
+### Function Signature Object (PEP 362)
+###############################################################################
+
+
+_WrapperDescriptor = type(type.__call__)
+_MethodWrapper = type(all.__call__)
+_ClassMethodWrapper = type(int.__dict__['from_bytes'])
+
+_NonUserDefinedCallables = (_WrapperDescriptor,
+                            _MethodWrapper,
+                            _ClassMethodWrapper,
+                            types.BuiltinFunctionType)
+
+
+def _signature_get_user_defined_method(cls, method_name):
+    """Private helper. Checks if ``cls`` has an attribute
+    named ``method_name`` and returns it only if it is a
+    pure python function.
+    """
+    try:
+        meth = getattr(cls, method_name)
+    except AttributeError:
+        return
+    else:
+        if not isinstance(meth, _NonUserDefinedCallables):
+            # Once '__signature__' will be added to 'C'-level
+            # callables, this check won't be necessary
+            return meth
+
+
+def _signature_get_partial(wrapped_sig, partial, extra_args=()):
+    """Private helper to calculate how 'wrapped_sig' signature will
+    look like after applying a 'functools.partial' object (or alike)
+    on it.
+    """
+
+    old_params = wrapped_sig.parameters
+    new_params = OrderedDict(old_params.items())
+
+    partial_args = partial.args or ()
+    partial_keywords = partial.keywords or {}
+
+    if extra_args:
+        partial_args = extra_args + partial_args
+
+    try:
+        ba = wrapped_sig.bind_partial(*partial_args, **partial_keywords)
+    except TypeError as ex:
+        msg = 'partial object {!r} has incorrect arguments'.format(partial)
+        raise ValueError(msg) from ex
+
+
+    transform_to_kwonly = False
+    for param_name, param in old_params.items():
+        try:
+            arg_value = ba.arguments[param_name]
+        except KeyError:
+            pass
+        else:
+            if param.kind is _POSITIONAL_ONLY:
+                # If positional-only parameter is bound by partial,
+                # it effectively disappears from the signature
+                new_params.pop(param_name)
+                continue
+
+            if param.kind is _POSITIONAL_OR_KEYWORD:
+                if param_name in partial_keywords:
+                    # This means that this parameter, and all parameters
+                    # after it should be keyword-only (and var-positional
+                    # should be removed). Here's why. Consider the following
+                    # function:
+                    #     foo(a, b, *args, c):
+                    #         pass
+                    #
+                    # "partial(foo, a='spam')" will have the following
+                    # signature: "(*, a='spam', b, c)". Because attempting
+                    # to call that partial with "(10, 20)" arguments will
+                    # raise a TypeError, saying that "a" argument received
+                    # multiple values.
+                    transform_to_kwonly = True
+                    # Set the new default value
+                    new_params[param_name] = param.replace(default=arg_value)
+                else:
+                    # was passed as a positional argument
+                    new_params.pop(param.name)
+                    continue
+
+            if param.kind is _KEYWORD_ONLY:
+                # Set the new default value
+                new_params[param_name] = param.replace(default=arg_value)
+
+        if transform_to_kwonly:
+            assert param.kind is not _POSITIONAL_ONLY
+
+            if param.kind is _POSITIONAL_OR_KEYWORD:
+                new_param = new_params[param_name].replace(kind=_KEYWORD_ONLY)
+                new_params[param_name] = new_param
+                new_params.move_to_end(param_name)
+            elif param.kind in (_KEYWORD_ONLY, _VAR_KEYWORD):
+                new_params.move_to_end(param_name)
+            elif param.kind is _VAR_POSITIONAL:
+                new_params.pop(param.name)
+
+    return wrapped_sig.replace(parameters=new_params.values())
+
+
+def _signature_bound_method(sig):
+    """Private helper to transform signatures for unbound
+    functions to bound methods.
+    """
+
+    params = tuple(sig.parameters.values())
+
+    if not params or params[0].kind in (_VAR_KEYWORD, _KEYWORD_ONLY):
+        raise ValueError('invalid method signature')
+
+    kind = params[0].kind
+    if kind in (_POSITIONAL_OR_KEYWORD, _POSITIONAL_ONLY):
+        # Drop first parameter:
+        # '(p1, p2[, ...])' -> '(p2[, ...])'
+        params = params[1:]
+    else:
+        if kind is not _VAR_POSITIONAL:
+            # Unless we add a new parameter type we never
+            # get here
+            raise ValueError('invalid argument type')
+        # It's a var-positional parameter.
+        # Do nothing. '(*args[, ...])' -> '(*args[, ...])'
+
+    return sig.replace(parameters=params)
+
+
+def _signature_is_builtin(obj):
+    """Private helper to test if `obj` is a callable that might
+    support Argument Clinic's __text_signature__ protocol.
+    """
+    return (isbuiltin(obj) or
+            ismethoddescriptor(obj) or
+            isinstance(obj, _NonUserDefinedCallables) or
+            # Can't test 'isinstance(type)' here, as it would
+            # also be True for regular python classes
+            obj in (type, object))
+
+
+def _signature_is_functionlike(obj):
+    """Private helper to test if `obj` is a duck type of FunctionType.
+    A good example of such objects are functions compiled with
+    Cython, which have all attributes that a pure Python function
+    would have, but have their code statically compiled.
+    """
+
+    if not callable(obj) or isclass(obj):
+        # All function-like objects are obviously callables,
+        # and not classes.
+        return False
+
+    name = getattr(obj, '__name__', None)
+    code = getattr(obj, '__code__', None)
+    defaults = getattr(obj, '__defaults__', _void) # Important to use _void ...
+    kwdefaults = getattr(obj, '__kwdefaults__', _void) # ... and not None here
+    annotations = getattr(obj, '__annotations__', None)
+
+    return (isinstance(code, types.CodeType) and
+            isinstance(name, str) and
+            (defaults is None or isinstance(defaults, tuple)) and
+            (kwdefaults is None or isinstance(kwdefaults, dict)) and
+            isinstance(annotations, dict))
+
+
+def _signature_get_bound_param(spec):
+    """ Private helper to get first parameter name from a
+    __text_signature__ of a builtin method, which should
+    be in the following format: '($param1, ...)'.
+    Assumptions are that the first argument won't have
+    a default value or an annotation.
+    """
+
+    assert spec.startswith('($')
+
+    pos = spec.find(',')
+    if pos == -1:
+        pos = spec.find(')')
+
+    cpos = spec.find(':')
+    assert cpos == -1 or cpos > pos
+
+    cpos = spec.find('=')
+    assert cpos == -1 or cpos > pos
+
+    return spec[2:pos]
+
+
+def _signature_strip_non_python_syntax(signature):
+    """
+    Private helper function. Takes a signature in Argument Clinic's
+    extended signature format.
+
+    Returns a tuple of three things:
+      * that signature re-rendered in standard Python syntax,
+      * the index of the "self" parameter (generally 0), or None if
+        the function does not have a "self" parameter, and
+      * the index of the last "positional only" parameter,
+        or None if the signature has no positional-only parameters.
+    """
+
+    if not signature:
+        return signature, None, None
+
+    self_parameter = None
+    last_positional_only = None
+
+    lines = [l.encode('ascii') for l in signature.split('\n')]
+    generator = iter(lines).__next__
+    token_stream = tokenize.tokenize(generator)
+
+    delayed_comma = False
+    skip_next_comma = False
+    text = []
+    add = text.append
+
+    current_parameter = 0
+    OP = token.OP
+    ERRORTOKEN = token.ERRORTOKEN
+
+    # token stream always starts with ENCODING token, skip it
+    t = next(token_stream)
+    assert t.type == tokenize.ENCODING
+
+    for t in token_stream:
+        type, string = t.type, t.string
+
+        if type == OP:
+            if string == ',':
+                if skip_next_comma:
+                    skip_next_comma = False
+                else:
+                    assert not delayed_comma
+                    delayed_comma = True
+                    current_parameter += 1
+                continue
+
+            if string == '/':
+                assert not skip_next_comma
+                assert last_positional_only is None
+                skip_next_comma = True
+                last_positional_only = current_parameter - 1
+                continue
+
+        if (type == ERRORTOKEN) and (string == '$'):
+            assert self_parameter is None
+            self_parameter = current_parameter
+            continue
+
+        if delayed_comma:
+            delayed_comma = False
+            if not ((type == OP) and (string == ')')):
+                add(', ')
+        add(string)
+        if (string == ','):
+            add(' ')
+    clean_signature = ''.join(text)
+    return clean_signature, self_parameter, last_positional_only
+
+
+def _signature_fromstr(cls, obj, s, skip_bound_arg=True):
+    """Private helper to parse content of '__text_signature__'
+    and return a Signature based on it.
+    """
+    # Lazy import ast because it's relatively heavy and
+    # it's not used for other than this function.
+    import ast
+
+    Parameter = cls._parameter_cls
+
+    clean_signature, self_parameter, last_positional_only = \
+        _signature_strip_non_python_syntax(s)
+
+    program = "def foo" + clean_signature + ": pass"
+
+    try:
+        module = ast.parse(program)
+    except SyntaxError:
+        module = None
+
+    if not isinstance(module, ast.Module):
+        raise ValueError("{!r} builtin has invalid signature".format(obj))
+
+    f = module.body[0]
+
+    parameters = []
+    empty = Parameter.empty
+    invalid = object()
+
+    module = None
+    module_dict = {}
+    module_name = getattr(obj, '__module__', None)
+    if module_name:
+        module = sys.modules.get(module_name, None)
+        if module:
+            module_dict = module.__dict__
+    sys_module_dict = sys.modules.copy()
+
+    def parse_name(node):
+        assert isinstance(node, ast.arg)
+        if node.annotation is not None:
+            raise ValueError("Annotations are not currently supported")
+        return node.arg
+
+    def wrap_value(s):
+        try:
+            value = eval(s, module_dict)
+        except NameError:
+            try:
+                value = eval(s, sys_module_dict)
+            except NameError:
+                raise RuntimeError()
+
+        if isinstance(value, (str, int, float, bytes, bool, type(None))):
+            return ast.Constant(value)
+        raise RuntimeError()
+
+    class RewriteSymbolics(ast.NodeTransformer):
+        def visit_Attribute(self, node):
+            a = []
+            n = node
+            while isinstance(n, ast.Attribute):
+                a.append(n.attr)
+                n = n.value
+            if not isinstance(n, ast.Name):
+                raise RuntimeError()
+            a.append(n.id)
+            value = ".".join(reversed(a))
+            return wrap_value(value)
+
+        def visit_Name(self, node):
+            if not isinstance(node.ctx, ast.Load):
+                raise ValueError()
+            return wrap_value(node.id)
+
+    def p(name_node, default_node, default=empty):
+        name = parse_name(name_node)
+        if name is invalid:
+            return None
+        if default_node and default_node is not _empty:
+            try:
+                default_node = RewriteSymbolics().visit(default_node)
+                o = ast.literal_eval(default_node)
+            except ValueError:
+                o = invalid
+            if o is invalid:
+                return None
+            default = o if o is not invalid else default
+        parameters.append(Parameter(name, kind, default=default, annotation=empty))
+
+    # non-keyword-only parameters
+    args = reversed(f.args.args)
+    defaults = reversed(f.args.defaults)
+    iter = itertools.zip_longest(args, defaults, fillvalue=None)
+    if last_positional_only is not None:
+        kind = Parameter.POSITIONAL_ONLY
+    else:
+        kind = Parameter.POSITIONAL_OR_KEYWORD
+    for i, (name, default) in enumerate(reversed(list(iter))):
+        p(name, default)
+        if i == last_positional_only:
+            kind = Parameter.POSITIONAL_OR_KEYWORD
+
+    # *args
+    if f.args.vararg:
+        kind = Parameter.VAR_POSITIONAL
+        p(f.args.vararg, empty)
+
+    # keyword-only arguments
+    kind = Parameter.KEYWORD_ONLY
+    for name, default in zip(f.args.kwonlyargs, f.args.kw_defaults):
+        p(name, default)
+
+    # **kwargs
+    if f.args.kwarg:
+        kind = Parameter.VAR_KEYWORD
+        p(f.args.kwarg, empty)
+
+    if self_parameter is not None:
+        # Possibly strip the bound argument:
+        #    - We *always* strip first bound argument if
+        #      it is a module.
+        #    - We don't strip first bound argument if
+        #      skip_bound_arg is False.
+        assert parameters
+        _self = getattr(obj, '__self__', None)
+        self_isbound = _self is not None
+        self_ismodule = ismodule(_self)
+        if self_isbound and (self_ismodule or skip_bound_arg):
+            parameters.pop(0)
+        else:
+            # for builtins, self parameter is always positional-only!
+            p = parameters[0].replace(kind=Parameter.POSITIONAL_ONLY)
+            parameters[0] = p
+
+    return cls(parameters, return_annotation=cls.empty)
+
+
+def _signature_from_builtin(cls, func, skip_bound_arg=True):
+    """Private helper function to get signature for
+    builtin callables.
+    """
+
+    if not _signature_is_builtin(func):
+        raise TypeError("{!r} is not a Python builtin "
+                        "function".format(func))
+
+    s = getattr(func, "__text_signature__", None)
+    if not s:
+        raise ValueError("no signature found for builtin {!r}".format(func))
+
+    return _signature_fromstr(cls, func, s, skip_bound_arg)
+
+
+def _signature_from_function(cls, func, skip_bound_arg=True):
+    """Private helper: constructs Signature for the given python function."""
+
+    is_duck_function = False
+    if not isfunction(func):
+        if _signature_is_functionlike(func):
+            is_duck_function = True
+        else:
+            # If it's not a pure Python function, and not a duck type
+            # of pure function:
+            raise TypeError('{!r} is not a Python function'.format(func))
+
+    s = getattr(func, "__text_signature__", None)
+    if s:
+        return _signature_fromstr(cls, func, s, skip_bound_arg)
+
+    Parameter = cls._parameter_cls
+
+    # Parameter information.
+    func_code = func.__code__
+    pos_count = func_code.co_argcount
+    arg_names = func_code.co_varnames
+    posonly_count = func_code.co_posonlyargcount
+    positional = arg_names[:pos_count]
+    keyword_only_count = func_code.co_kwonlyargcount
+    keyword_only = arg_names[pos_count:pos_count + keyword_only_count]
+    annotations = func.__annotations__
+    defaults = func.__defaults__
+    kwdefaults = func.__kwdefaults__
+
+    if defaults:
+        pos_default_count = len(defaults)
+    else:
+        pos_default_count = 0
+
+    parameters = []
+
+    non_default_count = pos_count - pos_default_count
+    posonly_left = posonly_count
+
+    # Non-keyword-only parameters w/o defaults.
+    for name in positional[:non_default_count]:
+        kind = _POSITIONAL_ONLY if posonly_left else _POSITIONAL_OR_KEYWORD
+        annotation = annotations.get(name, _empty)
+        parameters.append(Parameter(name, annotation=annotation,
+                                    kind=kind))
+        if posonly_left:
+            posonly_left -= 1
+
+    # ... w/ defaults.
+    for offset, name in enumerate(positional[non_default_count:]):
+        kind = _POSITIONAL_ONLY if posonly_left else _POSITIONAL_OR_KEYWORD
+        annotation = annotations.get(name, _empty)
+        parameters.append(Parameter(name, annotation=annotation,
+                                    kind=kind,
+                                    default=defaults[offset]))
+        if posonly_left:
+            posonly_left -= 1
+
+    # *args
+    if func_code.co_flags & CO_VARARGS:
+        name = arg_names[pos_count + keyword_only_count]
+        annotation = annotations.get(name, _empty)
+        parameters.append(Parameter(name, annotation=annotation,
+                                    kind=_VAR_POSITIONAL))
+
+    # Keyword-only parameters.
+    for name in keyword_only:
+        default = _empty
+        if kwdefaults is not None:
+            default = kwdefaults.get(name, _empty)
+
+        annotation = annotations.get(name, _empty)
+        parameters.append(Parameter(name, annotation=annotation,
+                                    kind=_KEYWORD_ONLY,
+                                    default=default))
+    # **kwargs
+    if func_code.co_flags & CO_VARKEYWORDS:
+        index = pos_count + keyword_only_count
+        if func_code.co_flags & CO_VARARGS:
+            index += 1
+
+        name = arg_names[index]
+        annotation = annotations.get(name, _empty)
+        parameters.append(Parameter(name, annotation=annotation,
+                                    kind=_VAR_KEYWORD))
+
+    # Is 'func' is a pure Python function - don't validate the
+    # parameters list (for correct order and defaults), it should be OK.
+    return cls(parameters,
+               return_annotation=annotations.get('return', _empty),
+               __validate_parameters__=is_duck_function)
+
+
+def _signature_from_callable(obj, *,
+                             follow_wrapper_chains=True,
+                             skip_bound_arg=True,
+                             sigcls):
+
+    """Private helper function to get signature for arbitrary
+    callable objects.
+    """
+
+    if not callable(obj):
+        raise TypeError('{!r} is not a callable object'.format(obj))
+
+    if isinstance(obj, types.MethodType):
+        # In this case we skip the first parameter of the underlying
+        # function (usually `self` or `cls`).
+        sig = _signature_from_callable(
+            obj.__func__,
+            follow_wrapper_chains=follow_wrapper_chains,
+            skip_bound_arg=skip_bound_arg,
+            sigcls=sigcls)
+
+        if skip_bound_arg:
+            return _signature_bound_method(sig)
+        else:
+            return sig
+
+    # Was this function wrapped by a decorator?
+    if follow_wrapper_chains:
+        obj = unwrap(obj, stop=(lambda f: hasattr(f, "__signature__")))
+        if isinstance(obj, types.MethodType):
+            # If the unwrapped object is a *method*, we might want to
+            # skip its first parameter (self).
+            # See test_signature_wrapped_bound_method for details.
+            return _signature_from_callable(
+                obj,
+                follow_wrapper_chains=follow_wrapper_chains,
+                skip_bound_arg=skip_bound_arg,
+                sigcls=sigcls)
+
+    try:
+        sig = obj.__signature__
+    except AttributeError:
+        pass
+    else:
+        if sig is not None:
+            if not isinstance(sig, Signature):
+                raise TypeError(
+                    'unexpected object {!r} in __signature__ '
+                    'attribute'.format(sig))
+            return sig
+
+    try:
+        partialmethod = obj._partialmethod
+    except AttributeError:
+        pass
+    else:
+        if isinstance(partialmethod, functools.partialmethod):
+            # Unbound partialmethod (see functools.partialmethod)
+            # This means, that we need to calculate the signature
+            # as if it's a regular partial object, but taking into
+            # account that the first positional argument
+            # (usually `self`, or `cls`) will not be passed
+            # automatically (as for boundmethods)
+
+            wrapped_sig = _signature_from_callable(
+                partialmethod.func,
+                follow_wrapper_chains=follow_wrapper_chains,
+                skip_bound_arg=skip_bound_arg,
+                sigcls=sigcls)
+
+            sig = _signature_get_partial(wrapped_sig, partialmethod, (None,))
+            first_wrapped_param = tuple(wrapped_sig.parameters.values())[0]
+            if first_wrapped_param.kind is Parameter.VAR_POSITIONAL:
+                # First argument of the wrapped callable is `*args`, as in
+                # `partialmethod(lambda *args)`.
+                return sig
+            else:
+                sig_params = tuple(sig.parameters.values())
+                assert (not sig_params or
+                        first_wrapped_param is not sig_params[0])
+                new_params = (first_wrapped_param,) + sig_params
+                return sig.replace(parameters=new_params)
+
+    if isfunction(obj) or _signature_is_functionlike(obj):
+        # If it's a pure Python function, or an object that is duck type
+        # of a Python function (Cython functions, for instance), then:
+        return _signature_from_function(sigcls, obj,
+                                        skip_bound_arg=skip_bound_arg)
+
+    if _signature_is_builtin(obj):
+        return _signature_from_builtin(sigcls, obj,
+                                       skip_bound_arg=skip_bound_arg)
+
+    if isinstance(obj, functools.partial):
+        wrapped_sig = _signature_from_callable(
+            obj.func,
+            follow_wrapper_chains=follow_wrapper_chains,
+            skip_bound_arg=skip_bound_arg,
+            sigcls=sigcls)
+        return _signature_get_partial(wrapped_sig, obj)
+
+    sig = None
+    if isinstance(obj, type):
+        # obj is a class or a metaclass
+
+        # First, let's see if it has an overloaded __call__ defined
+        # in its metaclass
+        call = _signature_get_user_defined_method(type(obj), '__call__')
+        if call is not None:
+            sig = _signature_from_callable(
+                call,
+                follow_wrapper_chains=follow_wrapper_chains,
+                skip_bound_arg=skip_bound_arg,
+                sigcls=sigcls)
+        else:
+            # Now we check if the 'obj' class has a '__new__' method
+            new = _signature_get_user_defined_method(obj, '__new__')
+            if new is not None:
+                sig = _signature_from_callable(
+                    new,
+                    follow_wrapper_chains=follow_wrapper_chains,
+                    skip_bound_arg=skip_bound_arg,
+                    sigcls=sigcls)
+            else:
+                # Finally, we should have at least __init__ implemented
+                init = _signature_get_user_defined_method(obj, '__init__')
+                if init is not None:
+                    sig = _signature_from_callable(
+                        init,
+                        follow_wrapper_chains=follow_wrapper_chains,
+                        skip_bound_arg=skip_bound_arg,
+                        sigcls=sigcls)
+
+        if sig is None:
+            # At this point we know, that `obj` is a class, with no user-
+            # defined '__init__', '__new__', or class-level '__call__'
+
+            for base in obj.__mro__[:-1]:
+                # Since '__text_signature__' is implemented as a
+                # descriptor that extracts text signature from the
+                # class docstring, if 'obj' is derived from a builtin
+                # class, its own '__text_signature__' may be 'None'.
+                # Therefore, we go through the MRO (except the last
+                # class in there, which is 'object') to find the first
+                # class with non-empty text signature.
+                try:
+                    text_sig = base.__text_signature__
+                except AttributeError:
+                    pass
+                else:
+                    if text_sig:
+                        # If 'obj' class has a __text_signature__ attribute:
+                        # return a signature based on it
+                        return _signature_fromstr(sigcls, obj, text_sig)
+
+            # No '__text_signature__' was found for the 'obj' class.
+            # Last option is to check if its '__init__' is
+            # object.__init__ or type.__init__.
+            if type not in obj.__mro__:
+                # We have a class (not metaclass), but no user-defined
+                # __init__ or __new__ for it
+                if (obj.__init__ is object.__init__ and
+                    obj.__new__ is object.__new__):
+                    # Return a signature of 'object' builtin.
+                    return sigcls.from_callable(object)
+                else:
+                    raise ValueError(
+                        'no signature found for builtin type {!r}'.format(obj))
+
+    elif not isinstance(obj, _NonUserDefinedCallables):
+        # An object with __call__
+        # We also check that the 'obj' is not an instance of
+        # _WrapperDescriptor or _MethodWrapper to avoid
+        # infinite recursion (and even potential segfault)
+        call = _signature_get_user_defined_method(type(obj), '__call__')
+        if call is not None:
+            try:
+                sig = _signature_from_callable(
+                    call,
+                    follow_wrapper_chains=follow_wrapper_chains,
+                    skip_bound_arg=skip_bound_arg,
+                    sigcls=sigcls)
+            except ValueError as ex:
+                msg = 'no signature found for {!r}'.format(obj)
+                raise ValueError(msg) from ex
+
+    if sig is not None:
+        # For classes and objects we skip the first parameter of their
+        # __call__, __new__, or __init__ methods
+        if skip_bound_arg:
+            return _signature_bound_method(sig)
+        else:
+            return sig
+
+    if isinstance(obj, types.BuiltinFunctionType):
+        # Raise a nicer error message for builtins
+        msg = 'no signature found for builtin function {!r}'.format(obj)
+        raise ValueError(msg)
+
+    raise ValueError('callable {!r} is not supported by signature'.format(obj))
+
+
+class _void:
+    """A private marker - used in Parameter & Signature."""
+
+
+class _empty:
+    """Marker object for Signature.empty and Parameter.empty."""
+
+
+class _ParameterKind(enum.IntEnum):
+    POSITIONAL_ONLY = 0
+    POSITIONAL_OR_KEYWORD = 1
+    VAR_POSITIONAL = 2
+    KEYWORD_ONLY = 3
+    VAR_KEYWORD = 4
+
+    def __str__(self):
+        return self._name_
+
+    @property
+    def description(self):
+        return _PARAM_NAME_MAPPING[self]
+
+_POSITIONAL_ONLY         = _ParameterKind.POSITIONAL_ONLY
+_POSITIONAL_OR_KEYWORD   = _ParameterKind.POSITIONAL_OR_KEYWORD
+_VAR_POSITIONAL          = _ParameterKind.VAR_POSITIONAL
+_KEYWORD_ONLY            = _ParameterKind.KEYWORD_ONLY
+_VAR_KEYWORD             = _ParameterKind.VAR_KEYWORD
+
+_PARAM_NAME_MAPPING = {
+    _POSITIONAL_ONLY: 'positional-only',
+    _POSITIONAL_OR_KEYWORD: 'positional or keyword',
+    _VAR_POSITIONAL: 'variadic positional',
+    _KEYWORD_ONLY: 'keyword-only',
+    _VAR_KEYWORD: 'variadic keyword'
+}
+
+
+class Parameter:
+    """Represents a parameter in a function signature.
+
+    Has the following public attributes:
+
+    * name : str
+        The name of the parameter as a string.
+    * default : object
+        The default value for the parameter if specified.  If the
+        parameter has no default value, this attribute is set to
+        `Parameter.empty`.
+    * annotation
+        The annotation for the parameter if specified.  If the
+        parameter has no annotation, this attribute is set to
+        `Parameter.empty`.
+    * kind : str
+        Describes how argument values are bound to the parameter.
+        Possible values: `Parameter.POSITIONAL_ONLY`,
+        `Parameter.POSITIONAL_OR_KEYWORD`, `Parameter.VAR_POSITIONAL`,
+        `Parameter.KEYWORD_ONLY`, `Parameter.VAR_KEYWORD`.
+    """
+
+    __slots__ = ('_name', '_kind', '_default', '_annotation')
+
+    POSITIONAL_ONLY         = _POSITIONAL_ONLY
+    POSITIONAL_OR_KEYWORD   = _POSITIONAL_OR_KEYWORD
+    VAR_POSITIONAL          = _VAR_POSITIONAL
+    KEYWORD_ONLY            = _KEYWORD_ONLY
+    VAR_KEYWORD             = _VAR_KEYWORD
+
+    empty = _empty
+
+    def __init__(self, name, kind, *, default=_empty, annotation=_empty):
+        try:
+            self._kind = _ParameterKind(kind)
+        except ValueError:
+            raise ValueError(f'value {kind!r} is not a valid Parameter.kind')
+        if default is not _empty:
+            if self._kind in (_VAR_POSITIONAL, _VAR_KEYWORD):
+                msg = '{} parameters cannot have default values'
+                msg = msg.format(self._kind.description)
+                raise ValueError(msg)
+        self._default = default
+        self._annotation = annotation
+
+        if name is _empty:
+            raise ValueError('name is a required attribute for Parameter')
+
+        if not isinstance(name, str):
+            msg = 'name must be a str, not a {}'.format(type(name).__name__)
+            raise TypeError(msg)
+
+        if name[0] == '.' and name[1:].isdigit():
+            # These are implicit arguments generated by comprehensions. In
+            # order to provide a friendlier interface to users, we recast
+            # their name as "implicitN" and treat them as positional-only.
+            # See issue 19611.
+            if self._kind != _POSITIONAL_OR_KEYWORD:
+                msg = (
+                    'implicit arguments must be passed as '
+                    'positional or keyword arguments, not {}'
+                )
+                msg = msg.format(self._kind.description)
+                raise ValueError(msg)
+            self._kind = _POSITIONAL_ONLY
+            name = 'implicit{}'.format(name[1:])
+
+        if not name.isidentifier():
+            raise ValueError('{!r} is not a valid parameter name'.format(name))
+
+        self._name = name
+
+    def __reduce__(self):
+        return (type(self),
+                (self._name, self._kind),
+                {'_default': self._default,
+                 '_annotation': self._annotation})
+
+    def __setstate__(self, state):
+        self._default = state['_default']
+        self._annotation = state['_annotation']
+
+    @property
+    def name(self):
+        return self._name
+
+    @property
+    def default(self):
+        return self._default
+
+    @property
+    def annotation(self):
+        return self._annotation
+
+    @property
+    def kind(self):
+        return self._kind
+
+    def replace(self, *, name=_void, kind=_void,
+                annotation=_void, default=_void):
+        """Creates a customized copy of the Parameter."""
+
+        if name is _void:
+            name = self._name
+
+        if kind is _void:
+            kind = self._kind
+
+        if annotation is _void:
+            annotation = self._annotation
+
+        if default is _void:
+            default = self._default
+
+        return type(self)(name, kind, default=default, annotation=annotation)
+
+    def __str__(self):
+        kind = self.kind
+        formatted = self._name
+
+        # Add annotation and default value
+        if self._annotation is not _empty:
+            formatted = '{}: {}'.format(formatted,
+                                       formatannotation(self._annotation))
+
+        if self._default is not _empty:
+            if self._annotation is not _empty:
+                formatted = '{} = {}'.format(formatted, repr(self._default))
+            else:
+                formatted = '{}={}'.format(formatted, repr(self._default))
+
+        if kind == _VAR_POSITIONAL:
+            formatted = '*' + formatted
+        elif kind == _VAR_KEYWORD:
+            formatted = '**' + formatted
+
+        return formatted
+
+    def __repr__(self):
+        return '<{} "{}">'.format(self.__class__.__name__, self)
+
+    def __hash__(self):
+        return hash((self.name, self.kind, self.annotation, self.default))
+
+    def __eq__(self, other):
+        if self is other:
+            return True
+        if not isinstance(other, Parameter):
+            return NotImplemented
+        return (self._name == other._name and
+                self._kind == other._kind and
+                self._default == other._default and
+                self._annotation == other._annotation)
+
+
+class BoundArguments:
+    """Result of `Signature.bind` call.  Holds the mapping of arguments
+    to the function's parameters.
+
+    Has the following public attributes:
+
+    * arguments : dict
+        An ordered mutable mapping of parameters' names to arguments' values.
+        Does not contain arguments' default values.
+    * signature : Signature
+        The Signature object that created this instance.
+    * args : tuple
+        Tuple of positional arguments values.
+    * kwargs : dict
+        Dict of keyword arguments values.
+    """
+
+    __slots__ = ('arguments', '_signature', '__weakref__')
+
+    def __init__(self, signature, arguments):
+        self.arguments = arguments
+        self._signature = signature
+
+    @property
+    def signature(self):
+        return self._signature
+
+    @property
+    def args(self):
+        args = []
+        for param_name, param in self._signature.parameters.items():
+            if param.kind in (_VAR_KEYWORD, _KEYWORD_ONLY):
+                break
+
+            try:
+                arg = self.arguments[param_name]
+            except KeyError:
+                # We're done here. Other arguments
+                # will be mapped in 'BoundArguments.kwargs'
+                break
+            else:
+                if param.kind == _VAR_POSITIONAL:
+                    # *args
+                    args.extend(arg)
+                else:
+                    # plain argument
+                    args.append(arg)
+
+        return tuple(args)
+
+    @property
+    def kwargs(self):
+        kwargs = {}
+        kwargs_started = False
+        for param_name, param in self._signature.parameters.items():
+            if not kwargs_started:
+                if param.kind in (_VAR_KEYWORD, _KEYWORD_ONLY):
+                    kwargs_started = True
+                else:
+                    if param_name not in self.arguments:
+                        kwargs_started = True
+                        continue
+
+            if not kwargs_started:
+                continue
+
+            try:
+                arg = self.arguments[param_name]
+            except KeyError:
+                pass
+            else:
+                if param.kind == _VAR_KEYWORD:
+                    # **kwargs
+                    kwargs.update(arg)
+                else:
+                    # plain keyword argument
+                    kwargs[param_name] = arg
+
+        return kwargs
+
+    def apply_defaults(self):
+        """Set default values for missing arguments.
+
+        For variable-positional arguments (*args) the default is an
+        empty tuple.
+
+        For variable-keyword arguments (**kwargs) the default is an
+        empty dict.
+        """
+        arguments = self.arguments
+        new_arguments = []
+        for name, param in self._signature.parameters.items():
+            try:
+                new_arguments.append((name, arguments[name]))
+            except KeyError:
+                if param.default is not _empty:
+                    val = param.default
+                elif param.kind is _VAR_POSITIONAL:
+                    val = ()
+                elif param.kind is _VAR_KEYWORD:
+                    val = {}
+                else:
+                    # This BoundArguments was likely produced by
+                    # Signature.bind_partial().
+                    continue
+                new_arguments.append((name, val))
+        self.arguments = dict(new_arguments)
+
+    def __eq__(self, other):
+        if self is other:
+            return True
+        if not isinstance(other, BoundArguments):
+            return NotImplemented
+        return (self.signature == other.signature and
+                self.arguments == other.arguments)
+
+    def __setstate__(self, state):
+        self._signature = state['_signature']
+        self.arguments = state['arguments']
+
+    def __getstate__(self):
+        return {'_signature': self._signature, 'arguments': self.arguments}
+
+    def __repr__(self):
+        args = []
+        for arg, value in self.arguments.items():
+            args.append('{}={!r}'.format(arg, value))
+        return '<{} ({})>'.format(self.__class__.__name__, ', '.join(args))
+
+
+class Signature:
+    """A Signature object represents the overall signature of a function.
+    It stores a Parameter object for each parameter accepted by the
+    function, as well as information specific to the function itself.
+
+    A Signature object has the following public attributes and methods:
+
+    * parameters : OrderedDict
+        An ordered mapping of parameters' names to the corresponding
+        Parameter objects (keyword-only arguments are in the same order
+        as listed in `code.co_varnames`).
+    * return_annotation : object
+        The annotation for the return type of the function if specified.
+        If the function has no annotation for its return type, this
+        attribute is set to `Signature.empty`.
+    * bind(*args, **kwargs) -> BoundArguments
+        Creates a mapping from positional and keyword arguments to
+        parameters.
+    * bind_partial(*args, **kwargs) -> BoundArguments
+        Creates a partial mapping from positional and keyword arguments
+        to parameters (simulating 'functools.partial' behavior.)
+    """
+
+    __slots__ = ('_return_annotation', '_parameters')
+
+    _parameter_cls = Parameter
+    _bound_arguments_cls = BoundArguments
+
+    empty = _empty
+
+    def __init__(self, parameters=None, *, return_annotation=_empty,
+                 __validate_parameters__=True):
+        """Constructs Signature from the given list of Parameter
+        objects and 'return_annotation'.  All arguments are optional.
+        """
+
+        if parameters is None:
+            params = OrderedDict()
+        else:
+            if __validate_parameters__:
+                params = OrderedDict()
+                top_kind = _POSITIONAL_ONLY
+                kind_defaults = False
+
+                for param in parameters:
+                    kind = param.kind
+                    name = param.name
+
+                    if kind < top_kind:
+                        msg = (
+                            'wrong parameter order: {} parameter before {} '
+                            'parameter'
+                        )
+                        msg = msg.format(top_kind.description,
+                                         kind.description)
+                        raise ValueError(msg)
+                    elif kind > top_kind:
+                        kind_defaults = False
+                        top_kind = kind
+
+                    if kind in (_POSITIONAL_ONLY, _POSITIONAL_OR_KEYWORD):
+                        if param.default is _empty:
+                            if kind_defaults:
+                                # No default for this parameter, but the
+                                # previous parameter of the same kind had
+                                # a default
+                                msg = 'non-default argument follows default ' \
+                                      'argument'
+                                raise ValueError(msg)
+                        else:
+                            # There is a default for this parameter.
+                            kind_defaults = True
+
+                    if name in params:
+                        msg = 'duplicate parameter name: {!r}'.format(name)
+                        raise ValueError(msg)
+
+                    params[name] = param
+            else:
+                params = OrderedDict((param.name, param) for param in parameters)
+
+        self._parameters = types.MappingProxyType(params)
+        self._return_annotation = return_annotation
+
+    @classmethod
+    def from_function(cls, func):
+        """Constructs Signature for the given python function.
+
+        Deprecated since Python 3.5, use `Signature.from_callable()`.
+        """
+
+        warnings.warn("inspect.Signature.from_function() is deprecated since "
+                      "Python 3.5, use Signature.from_callable()",
+                      DeprecationWarning, stacklevel=2)
+        return _signature_from_function(cls, func)
+
+    @classmethod
+    def from_builtin(cls, func):
+        """Constructs Signature for the given builtin function.
+
+        Deprecated since Python 3.5, use `Signature.from_callable()`.
+        """
+
+        warnings.warn("inspect.Signature.from_builtin() is deprecated since "
+                      "Python 3.5, use Signature.from_callable()",
+                      DeprecationWarning, stacklevel=2)
+        return _signature_from_builtin(cls, func)
+
+    @classmethod
+    def from_callable(cls, obj, *, follow_wrapped=True):
+        """Constructs Signature for the given callable object."""
+        return _signature_from_callable(obj, sigcls=cls,
+                                        follow_wrapper_chains=follow_wrapped)
+
+    @property
+    def parameters(self):
+        return self._parameters
+
+    @property
+    def return_annotation(self):
+        return self._return_annotation
+
+    def replace(self, *, parameters=_void, return_annotation=_void):
+        """Creates a customized copy of the Signature.
+        Pass 'parameters' and/or 'return_annotation' arguments
+        to override them in the new copy.
+        """
+
+        if parameters is _void:
+            parameters = self.parameters.values()
+
+        if return_annotation is _void:
+            return_annotation = self._return_annotation
+
+        return type(self)(parameters,
+                          return_annotation=return_annotation)
+
+    def _hash_basis(self):
+        params = tuple(param for param in self.parameters.values()
+                             if param.kind != _KEYWORD_ONLY)
+
+        kwo_params = {param.name: param for param in self.parameters.values()
+                                        if param.kind == _KEYWORD_ONLY}
+
+        return params, kwo_params, self.return_annotation
+
+    def __hash__(self):
+        params, kwo_params, return_annotation = self._hash_basis()
+        kwo_params = frozenset(kwo_params.values())
+        return hash((params, kwo_params, return_annotation))
+
+    def __eq__(self, other):
+        if self is other:
+            return True
+        if not isinstance(other, Signature):
+            return NotImplemented
+        return self._hash_basis() == other._hash_basis()
+
+    def _bind(self, args, kwargs, *, partial=False):
+        """Private method. Don't use directly."""
+
+        arguments = {}
+
+        parameters = iter(self.parameters.values())
+        parameters_ex = ()
+        arg_vals = iter(args)
+
+        while True:
+            # Let's iterate through the positional arguments and corresponding
+            # parameters
+            try:
+                arg_val = next(arg_vals)
+            except StopIteration:
+                # No more positional arguments
+                try:
+                    param = next(parameters)
+                except StopIteration:
+                    # No more parameters. That's it. Just need to check that
+                    # we have no `kwargs` after this while loop
+                    break
+                else:
+                    if param.kind == _VAR_POSITIONAL:
+                        # That's OK, just empty *args.  Let's start parsing
+                        # kwargs
+                        break
+                    elif param.name in kwargs:
+                        if param.kind == _POSITIONAL_ONLY:
+                            msg = '{arg!r} parameter is positional only, ' \
+                                  'but was passed as a keyword'
+                            msg = msg.format(arg=param.name)
+                            raise TypeError(msg) from None
+                        parameters_ex = (param,)
+                        break
+                    elif (param.kind == _VAR_KEYWORD or
+                                                param.default is not _empty):
+                        # That's fine too - we have a default value for this
+                        # parameter.  So, lets start parsing `kwargs`, starting
+                        # with the current parameter
+                        parameters_ex = (param,)
+                        break
+                    else:
+                        # No default, not VAR_KEYWORD, not VAR_POSITIONAL,
+                        # not in `kwargs`
+                        if partial:
+                            parameters_ex = (param,)
+                            break
+                        else:
+                            msg = 'missing a required argument: {arg!r}'
+                            msg = msg.format(arg=param.name)
+                            raise TypeError(msg) from None
+            else:
+                # We have a positional argument to process
+                try:
+                    param = next(parameters)
+                except StopIteration:
+                    raise TypeError('too many positional arguments') from None
+                else:
+                    if param.kind in (_VAR_KEYWORD, _KEYWORD_ONLY):
+                        # Looks like we have no parameter for this positional
+                        # argument
+                        raise TypeError(
+                            'too many positional arguments') from None
+
+                    if param.kind == _VAR_POSITIONAL:
+                        # We have an '*args'-like argument, let's fill it with
+                        # all positional arguments we have left and move on to
+                        # the next phase
+                        values = [arg_val]
+                        values.extend(arg_vals)
+                        arguments[param.name] = tuple(values)
+                        break
+
+                    if param.name in kwargs and param.kind != _POSITIONAL_ONLY:
+                        raise TypeError(
+                            'multiple values for argument {arg!r}'.format(
+                                arg=param.name)) from None
+
+                    arguments[param.name] = arg_val
+
+        # Now, we iterate through the remaining parameters to process
+        # keyword arguments
+        kwargs_param = None
+        for param in itertools.chain(parameters_ex, parameters):
+            if param.kind == _VAR_KEYWORD:
+                # Memorize that we have a '**kwargs'-like parameter
+                kwargs_param = param
+                continue
+
+            if param.kind == _VAR_POSITIONAL:
+                # Named arguments don't refer to '*args'-like parameters.
+                # We only arrive here if the positional arguments ended
+                # before reaching the last parameter before *args.
+                continue
+
+            param_name = param.name
+            try:
+                arg_val = kwargs.pop(param_name)
+            except KeyError:
+                # We have no value for this parameter.  It's fine though,
+                # if it has a default value, or it is an '*args'-like
+                # parameter, left alone by the processing of positional
+                # arguments.
+                if (not partial and param.kind != _VAR_POSITIONAL and
+                                                    param.default is _empty):
+                    raise TypeError('missing a required argument: {arg!r}'. \
+                                    format(arg=param_name)) from None
+
+            else:
+                if param.kind == _POSITIONAL_ONLY:
+                    # This should never happen in case of a properly built
+                    # Signature object (but let's have this check here
+                    # to ensure correct behaviour just in case)
+                    raise TypeError('{arg!r} parameter is positional only, '
+                                    'but was passed as a keyword'. \
+                                    format(arg=param.name))
+
+                arguments[param_name] = arg_val
+
+        if kwargs:
+            if kwargs_param is not None:
+                # Process our '**kwargs'-like parameter
+                arguments[kwargs_param.name] = kwargs
+            else:
+                raise TypeError(
+                    'got an unexpected keyword argument {arg!r}'.format(
+                        arg=next(iter(kwargs))))
+
+        return self._bound_arguments_cls(self, arguments)
+
+    def bind(self, /, *args, **kwargs):
+        """Get a BoundArguments object, that maps the passed `args`
+        and `kwargs` to the function's signature.  Raises `TypeError`
+        if the passed arguments can not be bound.
+        """
+        return self._bind(args, kwargs)
+
+    def bind_partial(self, /, *args, **kwargs):
+        """Get a BoundArguments object, that partially maps the
+        passed `args` and `kwargs` to the function's signature.
+        Raises `TypeError` if the passed arguments can not be bound.
+        """
+        return self._bind(args, kwargs, partial=True)
+
+    def __reduce__(self):
+        return (type(self),
+                (tuple(self._parameters.values()),),
+                {'_return_annotation': self._return_annotation})
+
+    def __setstate__(self, state):
+        self._return_annotation = state['_return_annotation']
+
+    def __repr__(self):
+        return '<{} {}>'.format(self.__class__.__name__, self)
+
+    def __str__(self):
+        result = []
+        render_pos_only_separator = False
+        render_kw_only_separator = True
+        for param in self.parameters.values():
+            formatted = str(param)
+
+            kind = param.kind
+
+            if kind == _POSITIONAL_ONLY:
+                render_pos_only_separator = True
+            elif render_pos_only_separator:
+                # It's not a positional-only parameter, and the flag
+                # is set to 'True' (there were pos-only params before.)
+                result.append('/')
+                render_pos_only_separator = False
+
+            if kind == _VAR_POSITIONAL:
+                # OK, we have an '*args'-like parameter, so we won't need
+                # a '*' to separate keyword-only arguments
+                render_kw_only_separator = False
+            elif kind == _KEYWORD_ONLY and render_kw_only_separator:
+                # We have a keyword-only parameter to render and we haven't
+                # rendered an '*args'-like parameter before, so add a '*'
+                # separator to the parameters list ("foo(arg1, *, arg2)" case)
+                result.append('*')
+                # This condition should be only triggered once, so
+                # reset the flag
+                render_kw_only_separator = False
+
+            result.append(formatted)
+
+        if render_pos_only_separator:
+            # There were only positional-only parameters, hence the
+            # flag was not reset to 'False'
+            result.append('/')
+
+        rendered = '({})'.format(', '.join(result))
+
+        if self.return_annotation is not _empty:
+            anno = formatannotation(self.return_annotation)
+            rendered += ' -> {}'.format(anno)
+
+        return rendered
+
+
+def signature(obj, *, follow_wrapped=True):
+    """Get a signature object for the passed callable."""
+    return Signature.from_callable(obj, follow_wrapped=follow_wrapped)
+
+
+def _main():
+    """ Logic for inspecting an object given at command line """
+    import argparse
+    import importlib
+
+    parser = argparse.ArgumentParser()
+    parser.add_argument(
+        'object',
+         help="The object to be analysed. "
+              "It supports the 'module:qualname' syntax")
+    parser.add_argument(
+        '-d', '--details', action='store_true',
+        help='Display info about the module rather than its source code')
+
+    args = parser.parse_args()
+
+    target = args.object
+    mod_name, has_attrs, attrs = target.partition(":")
+    try:
+        obj = module = importlib.import_module(mod_name)
+    except Exception as exc:
+        msg = "Failed to import {} ({}: {})".format(mod_name,
+                                                    type(exc).__name__,
+                                                    exc)
+        print(msg, file=sys.stderr)
+        sys.exit(2)
+
+    if has_attrs:
+        parts = attrs.split(".")
+        obj = module
+        for part in parts:
+            obj = getattr(obj, part)
+
+    if module.__name__ in sys.builtin_module_names:
+        print("Can't get info for builtin modules.", file=sys.stderr)
+        sys.exit(1)
+
+    if args.details:
+        print('Target: {}'.format(target))
+        print('Origin: {}'.format(getsourcefile(module)))
+        print('Cached: {}'.format(module.__cached__))
+        if obj is module:
+            print('Loader: {}'.format(repr(module.__loader__)))
+            if hasattr(module, '__path__'):
+                print('Submodule search path: {}'.format(module.__path__))
+        else:
+            try:
+                __, lineno = findsource(obj)
+            except Exception:
+                pass
+            else:
+                print('Line: {}'.format(lineno))
+
+        print('\n')
+    else:
+        print(getsource(obj))
+
+
+if __name__ == "__main__":
+    _main()