.NET Fiddle

CSharp · Console

/Program.cs

using System;
using System.Linq;
using System.Collections.Generic;

public class Program
{
	public static IEnumerable<string> Y()
	{
		var list = new List<string> {"1","2","3","4","5"};
		foreach(var i in list)
		{
			yield return i;
		}
	}
	
	public static void Main()
	{
		
		
		var ys = Y();
		Console.WriteLine("first ys");
		Console.WriteLine(string.Join(",", ys));
		IEnumerator<string> i = ys.GetEnumerator();
		Console.WriteLine(""+i.MoveNext()+": "+i.Current);
		Console.WriteLine(""+i.MoveNext()+": "+i.Current);
		Console.WriteLine(""+i.MoveNext()+": "+i.Current);
		Console.WriteLine(""+i.MoveNext()+": "+i.Current);
		Console.WriteLine(""+i.MoveNext()+": "+i.Current);
		Console.WriteLine(""+i.MoveNext()+": "+i.Current);
	}
}