code: func (h *Heartbeater) MaxAge() time.Duration {
  	if h.Interval() < 5*time.Second {
  		return h.Interval() + time.Second
  	}
  
  	return h.Interval() * 3 / 2
  }
docs: // MaxAge returns the maximum amount of time that can pass from the last tick of
  // an item before that item may be considered dead. By default, it is three
  // halves of the Interval() time, but is only one second if the interval time is
  // less than five seconds.