timing.go

package main

import (
	"fmt"
	"sync"
	"time"
)

func main() {
	var wg sync.WaitGroup
	wg.Add(1)
	go say("3 seconds", 3*time.Second, &wg)
	wg.Add(1)
	go say("2 seconds", 2*time.Second, &wg)
	wg.Add(1)
	go say("1 seconds", 1*time.Second, &wg)
	wg.Wait()
}

func say(text string, duration time.Duration, wg *sync.WaitGroup) {
	time.Sleep(duration)
	fmt.Println(text)
	wg.Done()
}