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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 publish(self, titles):
 """ Publish a set of episodes to the Podcast's RSS feed. :param titles: Either a single episode title or a sequence of episode titles to publish. """

        if isinstance(titles, Sequence) and not isinstance(titles, six.string_types):
            for title in titles:
                self.episodes[title].publish()
        elif isinstance(titles, six.string_types):
            self.episodes[titles].publish()
        else:
            raise TypeError('titles must be a string or a sequence of strings.')

        self.update_rss_feed()