code: func NewPinger() *Pinger {
  	rand.Seed(time.Now().UnixNano())
  	return &Pinger{
  		id:      rand.Intn(0xffff),
  		seq:     rand.Intn(0xffff),
  		addrs:   make(map[string]*net.IPAddr),
  		network: "ip",
  		source:  "",
  		source6: "",
  		hasIPv4: false,
  		hasIPv6: false,
  		Size:    TimeSliceLength,
  		MaxRTT:  time.Second,
  		OnRecv:  nil,
  		OnIdle:  nil,
  		Debug:   false,
  	}
  }
docs: // NewPinger returns a new Pinger struct pointer