go - Example for sync.WaitGroup correct?

Question

Is this example usage of sync.WaitGroup correct? It gives the expected result, but I am unsure about the wg.Add(4) and the position of wg.Done(). Does it make sense to add the four goroutines at once with wg.Add()?

http://play.golang.org/p/ecvYHiie0P

package main

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

func dosomething(millisecs time.Duration, wg *sync.WaitGroup) {
    duration := millisecs * time.Millisecond
    time.Sleep(duration)
    fmt.Println("Function in background, duration:", duration)
    wg.Done()
}

func main() {
    var wg sync.WaitGroup
    wg.Add(4)
    go dosomething(200, &wg)
    go dosomething(400, &wg)
    go dosomething(150, &wg)
    go dosomething(600, &wg)

    wg.Wait()
    fmt.Println("Done")
}

Result (as expected):

Function in background, duration: 150ms
Function in background, duration: 200ms
Function in background, duration: 400ms
Function in background, duration: 600ms
Done

Answer 1

Waitting for answers