using System;

using System.Threading;

using System.Collections.Generic;

using System.Threading.Tasks;

​

class Program

{

    static async Task Main()

    {

        var c = new CancellationTokenSource();

        await Task.WhenAll(new List<Task>(){ OuterThread().WaitAsync(c.Token), CancelAfterXSeconds(c, 5) });

    }

    public static async Task CancelAfterXSeconds(CancellationTokenSource c, int s)

    {

        await Task.Delay(1000 * s);

        c.Cancel();

    }

    public static async Task OuterThread()

    {

        Console.WriteLine("Outer 1");

        await Task.Delay(1000);

        Console.WriteLine("Outer 2");

        await Task.Delay(1000);

        Console.WriteLine("Outer 3");

        await Task.Delay(1000);

​

        _ = GenericThread("F&F Before");

        await GenericThread("Inner").ConfigureAwait(false);

        Console.WriteLine("Outer 4");

        await Task.Delay(1000);

        Console.WriteLine("Outer 5");

        await Task.Delay(1000);

        _ = GenericThread("F&F After");

        Console.WriteLine("Outer 6");

        await Task.Delay(1000);

        Console.WriteLine("Outer 7");

        await Task.Delay(1000);

    }

    public static async Task GenericThread(string prefix)

    {

        Console.WriteLine($"{prefix} 1");

        await Task.Delay(1000);

        Console.WriteLine($"{prefix} 2");

        await Task.Delay(1000);

        Console.WriteLine($"{prefix} 3");

        await Task.Delay(1000);

    }

}

​