def crash(self):
        """
        Fake L{IReactorCore.crash}.
        Sets C{self.running} to L{None}, because that feels crashy.
        Sets C{self.hasCrashed} to L{True}.
        """
        self.running = None
        self.hasCrashed = True

        Fake L{IReactorCore.crash}.
        Sets C{self.running} to L{None}, because that feels crashy.
        Sets C{self.hasCrashed} to L{True}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/testing.py