code: def run_callback(self, callback, *args):
          
          if self._loop is None:
              raise RuntimeError('hub is closed')
          elif not callable(callback):
              raise TypeError('"callback": expecting a callable')
          self._callbacks.append((callback, args))  # thread-safe
          self._interrupt_loop()
docs: Queue a callback.
  
          The *callback* will be called with positional arguments *args* in the
          next iteration of the event loop. If you add multiple callbacks, they
          will be called in the order that you added them. The callback will run
          in the Hub's fiber.
  
          This method is thread-safe: it is allowed to queue a callback from a
          different thread than the one running the Hub.