def crash(self):
        """
        See twisted.internet.interfaces.IReactorCore.crash.

        Reset reactor state tracking attributes and re-initialize certain
        state-transition helpers which were set up in C{__init__} but later
        destroyed (through use).
        """
        self._started = False
        self.running = False
        self.addSystemEventTrigger(
            'during', 'startup', self._reallyStartRunning)

        See twisted.internet.interfaces.IReactorCore.crash.

        Reset reactor state tracking attributes and re-initialize certain
        state-transition helpers which were set up in C{__init__} but later
        destroyed (through use).
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/base.py