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