code: def changeThreadEmoji(self, emoji, thread_id=None):
          
          thread_id, thread_type = self._getThread(thread_id, None)
  
          data = {"emoji_choice": emoji, "thread_or_other_fbid": thread_id}
          j = self._post(self.req_url.THREAD_EMOJI, data, fix_request=True, as_json=True)
docs: Changes thread color
  
          Trivia: While changing the emoji, the Facebook web client actually sends multiple different requests, though only this one is required to make the change
  
          :param color: New thread emoji
          :param thread_id: User/Group ID to change emoji of. See :ref:`intro_threads`
          :raises: FBchatException if request failed