using System;

using System.Collections.Generic;

public class Program

{

    private struct Maybe<T>

    {

        private readonly T value;

        private readonly bool hasValue;

​

        private Maybe(T value)

        {

            this.value = value;

            hasValue = true;

        }

​

        public static implicit operator Maybe<T>(T value)

        {

            return value == null ? new Maybe<T>() : new Maybe<T>(value);

        }

    }

    private static Maybe<byte> OK()

    {

        return 5;

    }

    private static Maybe<IEnumerable<byte>> NotOK()

    {

        IEnumerable<byte> a = new byte[] { 1, 2 };

        return a;

    }

}