code: func PeriodicThresholdChecker(check Checker, period time.Duration, threshold int) Checker {
  	tu := NewThresholdStatusUpdater(threshold)
  	go func() {
  		t := time.NewTicker(period)
  		for {
  			<-t.C
  			tu.Update(check.Check())
  		}
  	}()
  
  	return tu
  }
docs: // PeriodicThresholdChecker wraps an updater to provide a periodic checker that
  // uses a threshold before it changes status