using System;

public class Program

{

    public static void Main()

    {

        // With Nullable Object

        // to not throw exception

        Guid? id =  null;

        var test = id.ToString();

        Console.Write(test);

        // Without Nullable Object

        // throw exception

        // string id1 =  null;

        // var test1 = id1.ToString();

        // Console.Write(test1);

    }

}