code: def forum_topic_undelete(self, topic_id):
          
          return self._get('forum_topics/{0}/undelete.json'.format(topic_id),
                           method='POST', auth=True)
docs: Un delete a topic (Login requries) (Moderator+) (UNTESTED).
  
          Parameters:
              topic_id (int): Where topic_id is the topic id.