code: async def websocket_disconnect(self, message):
          
          # set this flag so as to ensure we don't send a downstream `websocket.close` message due to all
          # child applications closing.
          self.closing = True
          # inform all children
          await self.send_upstream(message)
          await super().websocket_disconnect(message)
docs: Handle the disconnect message.
  
          This is propagated to all upstream applications.