def METHOD_NAME(self):
    class A:
        __metaclass__ = abc.ABCMeta
    class OldstyleClass:
        pass
    self.assertFalse(isinstance(OldstyleClass, A))
    self.assertTrue(isinstance(OldstyleClass, type(OldstyleClass)))
    self.assertFalse(isinstance(A, OldstyleClass))
    # This raises a recursion depth error, but is low-priority:
    # self.assertTrue(isinstance(A, abc.ABCMeta))