code: func (n *Node) resetMasterDownInterval(advertInterval time.Duration) {
  	skewTime := (time.Duration((256 - int(n.Priority))) * (advertInterval)) / 256
  	masterDownInterval := 3*(advertInterval) + skewTime
  	if masterDownInterval != n.masterDownInterval {
  		n.masterDownInterval = masterDownInterval
  		log.Infof("resetMasterDownInterval: skewTime=%v, masterDownInterval=%v",
  			skewTime, masterDownInterval)
  	}
  }
docs: // resetMasterDownInterval calculates masterDownInterval per RFC 5798.