using System;
using System.Collections.Generic;
class IteratorDemo {
static IEnumerable OneTwoThree() {
Console.WriteLine("Returning 1");
yield return 1;
Console.WriteLine("Returning 2");
yield return 2;
Console.WriteLine("Returning 3");
yield return 3;
}
static void Main() {
foreach (var number in OneTwoThree()) {
Console.WriteLine(number);
}
}
}