using System;

using System.Security.Cryptography;

using System.Text;

using System.Threading;

using System.Threading.Tasks;

using System.Collections.Generic;

​

public class Program

{

    public static async Task Main()

    {

        var moo = new Moo();

        moo.Event += async ()=>

        {

            await Task.Delay(TimeSpan.FromSeconds(2));

            Console.WriteLine("hi");

        };

        moo.Event += async ()=>

        { 

            await Task.Delay(TimeSpan.FromMilliseconds(1));

            Console.WriteLine("jiri");

        };

​

        await moo.RaiseEventAsync();

        Console.WriteLine("await finished");

    }

    class Moo

    {

        public delegate Task AsyncEventHandler();

        public event AsyncEventHandler Event;

        public async Task RaiseEventAsync()

        {

            await (Event?.Invoke() ?? Task.CompletedTask);

        }

    }

}