using System;

    using System.Collections.Generic;

    var indx = new Indexed(5);

    public class Indexed

    {

        private List<string> srtl;

        public Indexed(int ii)

        {

            srtl = new List<string>();

            for (int i = 0; i < ii; i++)

                srtl.Add(i.ToString());

        }

        public string this[int index]

        {

            get => index < 5 ? "Foo" : "bar";

        }

    }