public class MonthsOfTheYear : IEnumerable
    {
        private string[] months =
        {
            "January",
            "February",
            "March",
            "April",
            "May",
            "June",
            "July",
            "August",
            "September",
            "October",
            "November",
            "December"
        };

        public IEnumerator GetEnumerator()
        {
            for (int index = 0; index < months.Length; index++)
            {
                // Yield връща всеки месец от годината.
                yield return months[index];
            }
        }
    }

//=================================================================

public class Program
    {
        static void Main(string[] args)
        {
            MonthsOfTheYear months = new MonthsOfTheYear();

            foreach (var month in months)
            {
                Console.WriteLine(month);
            }
        }
    }