public struct Nullable<T> where T : struct
{
    private readonly bool hasValue;
    internal T value;

    public readonly T Value
    {
        get
        {
            if (!hasValue)
            {
                ThrowHelper.ThrowInvalidOperationException_InvalidOperation_NoValue();
            }
            return value;
        }
    }

    public readonly T GetValueOrDefault() => value;
}