NonNullable.cs

using System;
using System.Collections.Generic;
using System.Text;

namespace System
{
    public struct NonNullable<T> where T : class
    {
        public NonNullable(T value)
        {
            if(value == null) { throw new ArgumentNullException(nameof(T)); }
            this.Value = value;
        }

        public T Value { get; private set; }

        public static implicit operator T(NonNullable<T> toConvert)
        {
            return toConvert.Value;
        }

        public static explicit operator NonNullable<T>(T value)
        {
            return new NonNullable<T>(value);
        }
    }
}