code: func (msg *MsgAddr) AddAddress(na *NetAddress) error {
  	if len(msg.AddrList)+1 > MaxAddrPerMsg {
  		str := fmt.Sprintf("too many addresses in message [max %v]",
  			MaxAddrPerMsg)
  		return messageError("MsgAddr.AddAddress", str)
  	}
  
  	msg.AddrList = append(msg.AddrList, na)
  	return nil
  }
docs: // AddAddress adds a known active peer to the message.