Practice closure in C#

Practice.csproj

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>netcoreapp2.1</TargetFramework>
  </PropertyGroup>

</Project>

Program.cs

using System;
using System.IO;
using System.Text;
using System.Threading;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Practice
{
    public class GuardTask
    {
        public void Run(string first, string second, Action callback)
        {
            Console.WriteLine($"GuardTask:Run: {first}");
            callback();
            Console.WriteLine($"GuardTask:Run: {second}");
        }
    }

    public static class TestHelpers
    {
        public static Action<Action> Subscribe(string first, string second)
        {
            return delegate (Action callback)
            {
                var guardTask = new GuardTask();
                guardTask.Run(first, second, callback);
            };
        }

        public static void WithCallback<T>(this Action<T> action, T callback)
            => action(callback);


        public static Action SendEmails()
        {
            return delegate
            {
                Console.WriteLine("SendEmails: Callback!");
            };
        }
    }

    class Program
    {
        static void Main(string[] args)
        {

            TestHelpers.Subscribe("first", "second")
                .WithCallback(TestHelpers.SendEmails());
        }
    }
}