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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 recover(self, requeue=False, cb=None):
        '''
        Ask server to redeliver all unacknowledged messages.
        '''
        args = Writer()
        args.write_bit(requeue)

        # The XML spec is incorrect; this method is always synchronous
        #  http://lists.rabbitmq.com/pipermail/rabbitmq-discuss/2011-January/010738.html
        self._recover_cb.append(cb)
        self.send_frame(MethodFrame(self.channel_id, 60, 110, args))
        self.channel.add_synchronous_cb(self._recv_recover_ok)