def doIteration(self, delay):
        """
        Do one iteration over the readers and writers which have been added.
        """
        raise NotImplementedError(
            reflect.qual(self.__class__) + " did not implement doIteration")

        Do one iteration over the readers and writers which have been added.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/base.py