using System;

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Will any line show a previous Guid?");

        var p = new Person();

        Console.WriteLine($"id : {p.Id}");

        Console.WriteLine($"id : {p.Id}");

        Console.WriteLine($"ref: {p.Ref}");

        Console.WriteLine($"ref: {p.Ref}");

    }

​

    internal sealed class Person

    {

        public Guid Id => Guid.NewGuid();

        public Guid Ref { get; } = Guid.NewGuid();

    }

}