def postApplication(self):
        """
        Instantiate a SignalCapturingMemoryReactor and start it
        in the runner.
        """
        reactor = SignalCapturingMemoryReactor()
        reactor._exitSignal = self._signalValue
        self.startReactor(reactor, sys.stdout, sys.stderr)

        Instantiate a SignalCapturingMemoryReactor and start it
        in the runner.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_twistd.py