def test_multipleReadersAndWriters(self):
        """
        Adding multiple readers and writers results in a single
        C{LoopingCall}.
        """
        poller = _ContinuousPolling(Clock())
        writer = object()
        poller.addWriter(writer)
        self.assertIsNotNone(poller._loop)
        poller.addWriter(object())
        self.assertIsNotNone(poller._loop)
        poller.addReader(object())
        self.assertIsNotNone(poller._loop)
        poller.addReader(object())
        poller.removeWriter(writer)
        self.assertIsNotNone(poller._loop)
        self.assertTrue(poller._loop.running)
        self.assertEqual(len(poller._reactor.getDelayedCalls()), 1)

        Adding multiple readers and writers results in a single
        C{LoopingCall}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/test/test_epollreactor.py