'Stop writing this request to the transport.  This can only be called
after C{writeTo} and before the L{Deferred} returned by C{writeTo}
fires.  It should cancel any asynchronous task started by C{writeTo}.
The L{Deferred} returned by C{writeTo} need not be fired if this method
is called.'

def stopWriting(self):

    _callAppFunction(self.bodyProducer.stopProducing)
