public sealed class Months: ValueObject<Months>
    {
        public static readonly string January = "January";
        public static readonly string February = "February";
        public static readonly string March = "March";
        public static readonly string April = "April";
        public static readonly string May = "May";
        public static readonly string June= "June";
        public static readonly string July = "July";
        public static readonly string August = "August";
        public static readonly string September = "September";
        public static readonly string October = "October";
        public static readonly string November = "November";
        public static readonly string December = "December";

        public IEnumerable<string> GetMonths()
        {
            yield return January;
            yield return February;
            yield return March;
            yield return April;
            yield return May;
            yield return June;
            yield return July;
            yield return August;
            yield return September;
            yield return October;
            yield return November;
            yield return December;
        }
    }