def METHOD_NAME(self):
    class Spam:
        def eggs(self):
            return "I am eggs."
    class SubSpam(Spam):
        pass
    class SubSubSpam(SubSpam):
        pass
    self.assertEqual(Spam().eggs(), "I am eggs.")
    self.assertEqual(SubSpam().eggs(), "I am eggs.")
    self.assertEqual(SubSubSpam().eggs(), "I am eggs.")