def test_identityPumpPolicy(self):
        """
        L{identityPumpPolicy} is a pump policy which calls the target's
        C{dataReceived} method one for each string in the queue passed to it.
        """
        bytes = []
        client = Protocol()
        client.dataReceived = bytes.append
        queue = loopback._LoopbackQueue()
        queue.put(b"foo")
        queue.put(b"bar")
        queue.put(None)

        loopback.identityPumpPolicy(queue, client)

        self.assertEqual(bytes, [b"foo", b"bar"])

        L{identityPumpPolicy} is a pump policy which calls the target's
        C{dataReceived} method one for each string in the queue passed to it.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_loopback.py