code: func NewAfterTimer(duration time.Duration, fn timer.Func) *timer.Timer {
  	return NewCountTimer(duration, 1, fn)
  }
docs: // NewAfterTimer returns a new Timer containing a function that will be called
  // after duration that specified by the duration argument.
  // The duration d must be greater than zero; if not, NewAfterTimer will panic.
  // Stop the timer to release associated resources.