$ ./python -c 'import unittest.mock'Traceback (most recent call last):  File "<string>", line 1, in <module>    import unittest.mock  File "/home/serhiy/py/cpython/Lib/unittest/mock.py", line 2233, in <module>    _CODE_SIG = inspect.signature(partial(CodeType.__init__, None))                ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^  File "/home/serhiy/py/cpython/Lib/inspect.py", line 3378, in signature    return Signature.from_callable(obj, follow_wrapped=follow_wrapped,           ~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^                                   globals=globals, locals=locals, eval_str=eval_str)                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^  File "/home/serhiy/py/cpython/Lib/inspect.py", line 3108, in from_callable    return _signature_from_callable(obj, sigcls=cls,           ~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^                                    follow_wrapper_chains=follow_wrapped,                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^                                    globals=globals, locals=locals, eval_str=eval_str)                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^  File "/home/serhiy/py/cpython/Lib/inspect.py", line 2603, in _signature_from_callable    wrapped_sig = _get_signature_of(obj.func)                  ~~~~~~~~~~~~~~~~~^^^^^^^^^^  File "/home/serhiy/py/cpython/Lib/inspect.py", line 2599, in _signature_from_callable    return _signature_from_builtin(sigcls, obj,           ~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^                                   skip_bound_arg=skip_bound_arg)                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^  File "/home/serhiy/py/cpython/Lib/inspect.py", line 2398, in _signature_from_builtin    raise ValueError("no signature found for builtin {!r}".format(func))ValueError: no signature found for builtin <slot wrapper '__init__' of 'object' objects>