code: def queue_call(self, delay, callback, *args, **kwds):
      
      if delay is None:
        self.current.append((callback, args, kwds))
        return
      if delay < 1e9:
        when = delay + self.clock.now()
      else:
        # Times over a billion seconds are assumed to be absolute.
        when = delay
      self.insort_event_right((when, callback, args, kwds))
docs: Schedule a function call at a specific time in the future.