Untitled

// 1
func worker() chan int {
	ch := make(chan int)
	go func() {
		time.Sleep(3 * time.Second)
		fmt.Println("worker done")
		ch <- 42
	}()
	return ch
}

func main() {
	timeStart := time.Now()
	_, _ = <-worker(), <-worker()
	fmt.Println(int(time.Since(timeStart).Seconds()))
}

// 2
func main() {
	m := make(map[int]*int)
	const n = 3
	for i := 0; i < n; i++ {
		m[i] = &i
	}

	for _, v := range m {
		fmt.Println(*v)
	}
}