def test_wrongTypeAncillary(self):
        """
        L{send1msg} will show a helpful exception message when given the wrong
        type of object for the 'ancillary' argument.
        """
        error = self.assertRaises(TypeError,
                                  send1msg, self.input.fileno(),
                                  "hello, world!", 0, 4321)
        self.assertEqual(str(error),
                         "send1msg argument 3 expected list, got int")

        L{send1msg} will show a helpful exception message when given the wrong
        type of object for the 'ancillary' argument.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/python/test/test_sendmsg.py