in later/unittest/backport/mock.py [0:0]
def _instance_callable(obj):
"""Given an object, return True if the object is callable.
For classes, return True if instances would be callable."""
if not isinstance(obj, type):
# already an instance
return getattr(obj, '__call__', None) is not None
# *could* be broken by a class overriding __mro__ or __dict__ via
# a metaclass
for base in (obj,) + obj.__mro__:
if base.__dict__.get('__call__') is not None:
return True
return False