NullabilityDemo.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Demo
{
    enum OriginShow
    {
        None,
        StarWars,
        StarTrek,
        Stargate,
        Babylon5,
        DrWho
    }

    class Program
    {
        static void Main(string[] args)
        {
            OriginShow? origin = null;

            Console.WriteLine(origin == OriginShow.StarTrek);  // False
            Console.WriteLine(origin == OriginShow.Stargate);  // False
            Console.WriteLine(origin == null);  // True

            origin = OriginShow.Stargate;

            Console.WriteLine(origin == OriginShow.StarTrek);  // False
            Console.WriteLine(origin == OriginShow.Stargate);  // True
            Console.WriteLine(origin == null);  // False

            Console.ReadLine();
        }

        void Write(bool value)
        {
            Console.WriteLine(value: value.ToString());
        }
    }
}