def test_responseFromMessageResponseType(self):
        """
        L{dns.Message._responseFromMessage} is a constructor function which
        generates a new I{answer} message from an existing L{dns.Message} like
        instance.
        """
        request = dns.Message()
        response = dns._responseFromMessage(responseConstructor=dns.Message,
                                            message=request)
        self.assertIsNot(request, response)

        L{dns.Message._responseFromMessage} is a constructor function which
        generates a new I{answer} message from an existing L{dns.Message} like
        instance.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/names/test/test_dns.py