def waitFor(self, event, handler):
        d = defer.Deferred()
        d.addCallback(handler)
        self.pipe.source.addOnetimeObserver(event, d.callback)
        return d
Observe an output event, returning a deferred.
dataset/ETHPy150Open kuri65536/python-for-android/python-modules/twisted/twisted/words/test/test_jabberclient.py/InitiatingInitializerHarness.waitFor