A Singleton superclass in C#

SingletonDemo.cs

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

namespace SingletonDemo
{
    public class Program
    {
        public static void Main(string[] args)
        {
            SampleClass.Instance.Test();
        }
    }
    
    public class Singleton<TSubclass> where TSubclass:Singleton<TSubclass>, new()  // das new zwingt die Subklasse, einen parameterlosen Konstruktor zu haben
    {
        private static TSubclass _instance;
        public static TSubclass Instance 
        {
            get 
            {
                if (_instance == null)
                    _instance = new TSubclass();
                return _instance;
            }
        }
    }
    
    public class SampleClass : Singleton<SampleClass>
    {
        public void Test()
        {
            Console.WriteLine("Hello world from the singleton");
        }
    }
}