channel
func main() { m := make(chan int64, 10) fmt.Println(len(m), cap(m))}func main() { var wg sync.WaitGroup for i := 0; i < 10; i++ { wg.Add(1) go func() { fmt.Println("Hello world") wg.Done() }() } wg.Wait()}func test3() { _ = make(map[chan interface{}]interface{})}