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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 ack(self, uid):
 """Acknowledge item as successfully consumed. Removes uid from ackbuffer and deletes the corresponding item. """

        self._redis.pipeline()\
                   .lrem(self.ACKBUF_KEY, 0, uid)\
                   .lrem(self.BACKUP, 0, uid)\
                   .hdel(self.ITEMS_KEY, uid)\
                   .execute()