using System;

using System.Collections.Generic;

// see: https://stackoverflow.com/a/231945/1016343

public class Program

{

    public static void Main()

    {

        foreach (var e in GetEnumerator()) { e.Dump(); }

    }

    public static IEnumerable<int> GetEnumerator()

    {

        int i = 0;

        while (true)

        {

            if (i < 5)

            {

                yield return i;

            }

            else

            {

                // note that i++ will not be executed after this

                yield break;

            }

            i++;

        }

    }

}