def test_orderedDifferentConstants_le(self):
        """
        L{twisted.python.constants._Constant.__le__} returns C{NotImplemented}
        when comparing constants of different types.
        """
        self.assertEqual(
            NotImplemented,
            NamedLetters.alpha.__le__(ValuedLetters.alpha)
        )

        L{twisted.python.constants._Constant.__le__} returns C{NotImplemented}
        when comparing constants of different types.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/python/test/test_constants.py