code: def changeNickname(
          self, nickname, user_id, thread_id=None, thread_type=ThreadType.USER
      ):
          
          thread_id, thread_type = self._getThread(thread_id, thread_type)
  
          data = {
              "nickname": nickname,
              "participant_id": user_id,
              "thread_or_other_fbid": thread_id,
          }
          j = self._post(
              self.req_url.THREAD_NICKNAME, data, fix_request=True, as_json=True
          )
docs: Changes the nickname of a user in a thread
  
          :param nickname: New nickname
          :param user_id: User that will have their nickname changed
          :param thread_id: User/Group ID to change color of. See :ref:`intro_threads`
          :param thread_type: See :ref:`intro_threads`
          :type thread_type: models.ThreadType
          :raises: FBchatException if request failed