code: func WaitUntil(fn ConditionFn, timeout time.Duration) bool {
  	deadline := time.Now().Add(timeout)
  	for time.Now().Before(deadline) {
  		if fn() {
  			return true
  		}
  		time.Sleep(100 * time.Millisecond)
  	}
  	return false
  }
docs: // WaitUntil returns true if the condition specified evaluated to
  // true before the timeout, false otherwise.