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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def stop(self):
 """ Stop the queue-consumer gracefully. Wait until the last provider has been unregistered and for the ConsumerMixin's greenthread to exit (i.e. until all pending messages have been acked or requeued and all consumers stopped). """

        if not self._consumers_ready.ready():
            _log.debug('stopping while consumer is starting %s', self)

            stop_exc = QueueConsumerStopped()

            # stopping before we have started successfully by brutally
            # killing the consumer thread as we don't have a way to hook
            # into the pre-consumption startup process
            self._gt.kill(stop_exc)

        self.wait_for_providers()

        try:
            _log.debug('waiting for consumer death %s', self)
            self._gt.wait()
        except QueueConsumerStopped:
            pass

        super(QueueConsumer, self).stop()
        _log.debug('stopped %s', self)