async for yarin

yarin.cs

    rivate static void Main()
    {
        CountToFiftyAsync().Wait();
    }

    private static async Task CountToFiftyAsync()
    {
        var taskA = CountToAsync("a", 10);
        var taskB = CountToAsync("b", 10);
        var taskC = CountToAsync("c", 10);
        var taskD = CountToAsync("d", 10);
        var taskE = CountToAsync("e", 10);
        
        await Task.WhenAll(taskA, taskB, taskC, taskD, taskE);
    }

    private static async Task CountToAsync(string key, int countTo)
    {
        for (int i = 0; i < countTo; i++)
        {
            await Task.Delay(1000);
            Console.WriteLine("{0}: {1}", key, i + 1);
        }
    }