package main

import "fmt"

type NetMsg interface {
	Pack() []byte
}

type MsgToken struct {
	Token [4]byte
}

func (t MsgToken) Pack() []byte {
	return t.Token[:]
}

func main() {
	messages := []NetMsg{
		MsgToken {
			Token: [4]byte{0xff, 0xff, 0xff, 0xff},
		},
	}

	for i,msg := range messages {
		if token, ok := msg.(MsgToken); ok {
			token.Token = [4]byte{0x00, 0x00, 0x00, 0x00}
			messages[i] = token
		}
	}

	fmt.Printf("messages: %v\n", messages)
}