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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 topics(self):
 """Get all topics the user is authorized to view. Returns: set: topics """

        cluster = self._client.cluster
        if self._client._metadata_refresh_in_progress and self._client._topics:
            future = cluster.request_update()
            self._client.poll(future=future)
        stash = cluster.need_all_topic_metadata
        cluster.need_all_topic_metadata = True
        future = cluster.request_update()
        self._client.poll(future=future)
        cluster.need_all_topic_metadata = stash
        return cluster.topics()