public void DeriveWithSelectorModifyTwo()
{
var list = new RxList<string>("1", "2", "3");
var derived = list.Derive(x => int.Parse(x));
list.ModifyRange(new[] { new RxListItem<string>(0, "4"), new RxListItem<string>(2, "5") });
Assert.AreEqual(4, derived[0]);
Assert.AreEqual(2, derived[1]);
Assert.AreEqual(5, derived[2]);
}