Class E

Lib/test/test_abc.py:187–188

                self.assertRaises(TypeError, D)  # because foo is still abstract
                self.assertTrue(isabstract(D))
                class E(D):
                    def foo(self): pass
                self.assertEqual(E.__abstractmethods__, set())
                E()  # now foo is concrete, too
                self.assertFalse(isabstract(E))