Waiting for all running goroutines to complete

Modify the program so that the main function waits for all launched goroutines to complete before exiting.

package main

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

func main() {
    var wg sync.WaitGroup

    for i := 0; i < 10; i++ {
        wg.Add(1)
        go func(i int) {
            defer wg.Done()
            printNumber(i)
        }(i)
    }

    wg.Wait()
}

func printNumber(n int) {
    time.Sleep(time.Second)
    fmt.Println(n)
}