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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 _encoded_routing_key(self):
 """The encoded routing key used to publish the message on the broker."""

        topic = self.topic
        if config.conf["topic_prefix"]:
            topic = ".".join((config.conf["topic_prefix"].rstrip("."), topic))
        return topic.encode("utf-8")