Class M3

Lib/test/test_patma.py:53–54

        class M2(C, collections.UserDict, collections.abc.Sequence):
            pass
        class M3(collections.UserDict, C, list):
            pass
        class M4(dict, collections.abc.Sequence, C):
            pass
        self.assertEqual(self.check_sequence_then_mapping(M1()), "map")