code: def fetchUnseen(self):
          
          j = self._post(
              self.req_url.UNSEEN_THREADS, None, fix_request=True, as_json=True
          )
  
          payload = j["payload"]["unseen_thread_fbids"][0]
          return payload["thread_fbids"] + payload["other_user_fbids"]
docs: Get the unseen (new) thread list
  
          :return: List of unseen thread ids
          :rtype: list
          :raises: FBchatException if request failed