using System;

using System.Collections.Generic;

public class Program

{

    public class X {

        public string a { get; set; } = null;

    }

    public static void Main()

    {

        var list = new List<X>() {

            new X() { a = "Toast" },

            new X(),

            null

        };

        foreach (var x in list) {

            Console.WriteLine("result: " + (x?.a ?? "test"));

        }

    }

}