def METHOD_NAME(self):
    TestConfigurable.configure(TestConfig2)
    obj = TestConfigurable()
    self.assertIsInstance(obj, TestConfig2)
    self.assertIs(obj.b, None)
    obj = TestConfigurable(b=2)
    self.assertIsInstance(obj, TestConfig2)
    self.assertEqual(obj.b, 2)
    self.checkSubclasses()