using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var sideeffect = 0;

        var list = Enumerable.Range(1, 10).Select(i => {

            // prove when it's enumerated

            sideeffect++;

            return i;

        });

        // will 'enumerate' one item!

        if(list.Any()) Console.WriteLine("There are items in the list; sideeffect={0}", sideeffect);

        foreach(var item in list) {

            Console.WriteLine("Item {0} enumerated; sideeffect={1}", item, sideeffect);

        }

    }

}