func foo() {
    fmt.Println(runtime.NumGoroutine())
    time.Sleep(1000)
    fmt.Println(runtime.NumGoroutine())
}

func main() {
    fmt.Println(runtime.NumGoroutine())
    foo()
    fmt.Println(runtime.NumGoroutine())
}

/// out:
1
1
1
1

func foo(wg *sync.WaitGroup) {
    fmt.Println(runtime.NumGoroutine())
    time.Sleep(1000)
    fmt.Println(runtime.NumGoroutine())
    wg.Done()
}


func main() {
    fmt.Println(runtime.NumGoroutine())
    wg := &sync.WaitGroup{}
    wg.Add(1)
    go foo(wg)
    fmt.Println(runtime.NumGoroutine())
    wg.Wait()
    fmt.Println(runtime.NumGoroutine())
}

/// out:
1
2
2
2
1

A goroutine is a lightweight thread managed by the Go runtime.

string message = (await CountRecordsAsync()) switch
{
    0 => "No records found.",
    > 10 => "Too many records to display.",
    _ => "Insanely many records."
};

static async void MyDelay() {
    await Task.Delay(....)
}

func MyDelay() {
    time.Sleep(...)
}

static async void MyDelay() {
    Task.Delay(....)
}

func MyDelay() {
    go time.Sleep(...)
}

get_result() ->
  spawn(parall1),
  spawn(parall2),
  spawn(parall3),
  receive
    {parall1, Result} -> Result;
    {parall2, Result2} -> Result2;
    {parall3, Result3} -> Result3;
  end.

SD>get_result() ->
SD>  spawn(parall1),
SD>  spawn(parall2),
SD>  spawn(parall3),
SD>  receive
SD>    {parall1, Result} -> Result;
SD>    {parall2, Result2} -> Result2;
SD>    {parall3, Result3} -> Result3;
SD>  end.
SD>

public static async Task<T> GetResultAsync()
{
    var task1 = parall1();
    var task2 = parall2();
    var task3 = parall3();

    return Task.WhenAny(task1, task2, task3) switch
    {
        task1 => await task1;
        task2 => await task2;
        task2 => await task3;
    };       
};

    return await Task.WhenAny(task1, task2, task3);

static async Task<string> Para1(int delay)
{
    await Task.Delay(delay);
    return $"Finished in {delay} ms";
}

//в этой одной строке - 3 запустятся в параллель, результатом будет та, которая первой ответила
var t = await Task.WhenAny(Para1(2000), Para1(100), Para1(500));
Console.WriteLine(t.Result); //вместо t.Result можно использовать await t

result := make(chan int)
go func(){result <- prime(10000)}()
// Куча кода
return <-result