using System;

using System.Threading.Tasks;

public class Program

{

    public static async Task<(int, string)> ReadOne()

    {

        var tcs = new TaskCompletionSource<(int, string)>(); 

        await Task.Run(() => {

            Task.Delay(4000).Wait(); // Simulate one message

            tcs.SetResult((0, "Success"));

        });

        return await tcs.Task;

    }

    public static async Task Main()

    {

        (var errcode, var errmsg) = await ReadOne();

        Console.WriteLine($"Result: {errcode}, {errmsg}");

    }

}