using System;

public class Program

{

    public static void Main()

    {

        new Test().SayHelloWorld();

    }

}

​

class Test

{

    private readonly Lazy<string> HelloWorld;

    public Test()

    {

        HelloWorld = new Lazy<string>(() => "Hello World!");

    }

    public void SayHelloWorld()

    {

        Console.WriteLine(HelloWorld.Value);

    }

}