def test_cancelDeferredListCallback(self):
        """
        When cancelling an unfired L{defer.DeferredList} without the
        C{fireOnOneCallback} and C{fireOnOneErrback} flags set, the
        L{defer.DeferredList} will be callback with a C{list} of
        (success, result) C{tuple}s.
        """
        deferredOne = defer.Deferred(fakeCallbackCanceller)
        deferredTwo = defer.Deferred()
        deferredList = defer.DeferredList([deferredOne, deferredTwo])
        deferredList.cancel()
        self.failureResultOf(deferredTwo, defer.CancelledError)
        result = self.successResultOf(deferredList)
        self.assertTrue(result[0][0])
        self.assertEqual(result[0][1], "Callback Result")
        self.assertFalse(result[1][0])
        self.assertTrue(result[1][1].check(defer.CancelledError))

        When cancelling an unfired L{defer.DeferredList} without the
        C{fireOnOneCallback} and C{fireOnOneErrback} flags set, the
        L{defer.DeferredList} will be callback with a C{list} of
        (success, result) C{tuple}s.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_defer.py