def callLater(self, period, func):
        """
        Wrapper around
        L{reactor.callLater<twisted.internet.interfaces.IReactorTime.callLater>}
        for test purpose.
        """
        from twisted.internet import reactor
        return reactor.callLater(period, func)

        Wrapper around
        L{reactor.callLater<twisted.internet.interfaces.IReactorTime.callLater>}
        for test purpose.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/protocols/policies.py