how to define uuid in golang code example

Example: golang generate uuid

package main

import (
	"fmt"
	"crypto/rand"
	"log"
)

func main() {
	b := make([]byte, 16)
	_, err := rand.Read(b)
	if err != nil {
    		log.Fatal(err)
	}
	uuid := fmt.Sprintf("%x-%x-%x-%x-%x",
    	b[0:4], b[4:6], b[6:8], b[8:10], b[10:])
	fmt.Println(uuid)
}