Simple generation UUID in golang

uuid.go

package main

import (
	"encoding/hex"
	"fmt"
	"math/rand"
	"time"
	
)

func uuid() string {
    	token := make([]byte, 18)
   	rand.Read(token)
	result := make([]byte, 36)
	hex.Encode(result, token)
	
	result[8] = 45
	result[13] = 45
	result[18] = 45
	result[23] = 45

	return string(result)
}

func main() {
	rand.Seed(time.Now().UnixNano()) // optional
	
	fmt.Println(uuid()) // 0c204d39-00fd-d3f1-20ca-007e91c7d029
}