AsyncActionTest.cs

using System;
using System.Threading.Tasks;

namespace TestOp
{
	class MainClass
	{
		public static void Main (string[] args)
		{
			var foo = new foo();
			foo.Run();
			Console.ReadLine();
		}
	}

	public class foo

	{
		string token;

		public foo ()
		{
			this.token = "Initial Value";
		}

		Task DoIt(string someString)
		{
			return Task.Delay(0).ContinueWith(t => Console.WriteLine("SomeString is '{0}'", someString));
		}

		async Task Execute(Func<Task> op)
		{
			await op();
		}

		public async void Run()
		{
			var op = DoIt(this.token);
			this.token = "Changed value";
			await Execute(() => op);
		}
	}
}