docs: def archive_feed(self, feed_id, feed):
          """
          Archive a feed
          :param feed_id: the feed id of the feed to archive
          :param feed: the feed to archive
          """
          with open(self.feed_repository + '/' + str(feed_id) + '.xml', 'w') as rec_file:
              rec_file.write(feed.atom_str(pretty=True))
          if feed_id == self.current_feed.id:
              self._current_feed = None