'Record that the request is finished and callback and L{Deferred}s
waiting for notification of this.'

def finish(self):

    self.finished = (self.finished + 1)
    if (self._finishedDeferreds is not None):
        observers = self._finishedDeferreds
        self._finishedDeferreds = None
        for obs in observers:
            obs.callback(None)
