package main import ( "fmt" "sync" ) func add_num(a, b int, done func()) { defer done() c := a + b fmt.Printf("%d + %d = %d\n", a, b, c) } func main() { var wg sync.WaitGroup for i := 0; i < 10; i++ { go add_num(i, 1, wg.Done) } wg.Add(10) wg.Wait() println("nnni") }