def test_getsMultipleWithEmpty(self):
        """
        When getting a non-available key with L{MemCacheProtocol.getMultiple}
        when C{withIdentifier} is C{True}, the other keys are retrieved
        correctly, and the non-available key gets a tuple of C{0} as flag,
        L{None} as value, and an empty cas value.
        """
        return self._test(
            self.proto.getMultiple([b"foo", b"bar"], True),
            b"gets foo bar\r\n",
            b"VALUE foo 0 3 1234\r\negg\r\nEND\r\n",
            {b'bar': (0, b'', None), b'foo': (0, b'1234', b'egg')})

        When getting a non-available key with L{MemCacheProtocol.getMultiple}
        when C{withIdentifier} is C{True}, the other keys are retrieved
        correctly, and the non-available key gets a tuple of C{0} as flag,
        L{None} as value, and an empty cas value.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_memcache.py