using System;

using System.Collections.Generic;

using System.Threading;

using System.Threading.Tasks;           

class Program

{

    static public async Task Test()

    {

        System.Console.WriteLine("Enter Test");

        await Task.Delay(2000);

        System.Console.WriteLine("Leave Test");

    }

​

    public static async Task Main()

    {

        await Test().ContinueWith(

        async (task) =>

        {

            System.Console.WriteLine("Enter callback");

            await Task.Delay(1000);

            System.Console.WriteLine("Leave callback");

        },

        TaskContinuationOptions.AttachedToParent).Unwrap();

        Console.WriteLine("Done with test");

    }

}