def deferred(self):
        """
        DEPRECATED. L{Deferred} fired when loop stops or fails.

        Use the L{Deferred} returned by L{LoopingCall.start}.
        """
        warningString = _getDeprecationWarningString(
            "twisted.internet.task.LoopingCall.deferred",
            Version("Twisted", 16, 0, 0),
            replacement='the deferred returned by start()')
        warnings.warn(warningString, DeprecationWarning, stacklevel=2)

        return self._deferred

        DEPRECATED. L{Deferred} fired when loop stops or fails.

        Use the L{Deferred} returned by L{LoopingCall.start}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/task.py