class Program
{
    public static IEnumerable<string> MyListOfStrings(string[] sa)
    {
        foreach (var s in sa)
        {
            Console.WriteLine("about to yield return");
            yield return s;
        }
    }

    static void Main(string[] args)
    {
        string[] sa = new[] {
            "aaa",
            "bbb",
            "ccc"
        };

        foreach (string s in MyListOfStrings(sa))
            Console.WriteLine(s);
    }
}