Class B_tuple

Lib/test/test_descr.py:4334–4335

            def __repr__(self):
                return '<A_tuple>'
        class B_tuple(tuple):
            __slots__ = ()
        b = B_tuple((1, 2))
        with self.assertRaisesRegex(TypeError, 'layout differs'):
            B_tuple.__bases__ = (object,)