code: def blockUser(self, user_id):
          
          data = {"fbid": user_id}
          r = self._post(self.req_url.BLOCK_USER, data)
          return r.ok
docs: Blocks messages from a specifed user
  
          :param user_id: The ID of the user that you want to block
          :return: Whether the request was successful
          :raises: FBchatException if request failed