def test_interfaces(self):
        """
        L{StringTransport} instances provide L{ITransport}, L{IPushProducer},
        and L{IConsumer}.
        """
        self.assertTrue(verifyObject(ITransport, self.transport))
        self.assertTrue(verifyObject(IPushProducer, self.transport))
        self.assertTrue(verifyObject(IConsumer, self.transport))

        L{StringTransport} instances provide L{ITransport}, L{IPushProducer},
        and L{IConsumer}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/test/test_testing.py