code: def on_exit_stage(self):
          
  
          # 1. Let the forum react to the end of the game.  Local forums don't 
          #    react to this, but remote forums take the opportunity to stop 
          #    trying to extract tokens from messages.
  
          self.forum.on_finish_game()
  
          # 2. Let the actors react to the end of the game.
  
          for actor in self.actors:
              actor.on_finish_game()
  
          # 3. Let the world react to the end of the game.
  
          with self.world._unlock_temporarily():
              self.world.on_finish_game()
docs: Give the actors, the world, and the messaging system a chance to react 
          to the end of the game.