code: def publish(self, titles):
          
          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()
docs: 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.