code: func PollUntil(interval time.Duration, condition ConditionFunc, stopCh <-chan struct{}) error {
  	ctx, cancel := contextForChannel(stopCh)
  	defer cancel()
  	return WaitFor(poller(interval, 0), condition, ctx.Done())
  }
docs: // PollUntil tries a condition func until it returns true, an error or stopCh is
  // closed.
  //
  // PollUntil always waits interval before the first run of 'condition'.
  // 'condition' will always be invoked at least once.