def test_decrement(self):
        """
        Test decrementing a variable: L{MemCacheProtocol.decrement} returns a
        L{Deferred} which is called back with the decremented value of the
        given key.
        """
        return self._test(
            self.proto.decrement(b"foo"), b"decr foo 1\r\n", b"5\r\n", 5)

        Test decrementing a variable: L{MemCacheProtocol.decrement} returns a
        L{Deferred} which is called back with the decremented value of the
        given key.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_memcache.py