@withActionContext
    def test_addBothReturnsSelf(self):
        result = Deferred()
        context = DeferredContext(result)
        self.assertIs(context, context.addBoth(lambda x: None))
L{DeferredContext.addBoth} returns the L{DeferredContext}.
dataset/ETHPy150Open ClusterHQ/eliot/eliot/tests/test_twisted.py/DeferredContextTests.test_addBothReturnsSelf