static void Main()
{
var strs = Enumerable.Range(0, 1000).Select(i => i.ToString());
var myAbc = new abc <string>(
xs => xs.OrderByDescending(x => x.Length).ThenByDescending(x => x.Substring(1))
);
myAbc.someMethod(strs); //5, 6, 7, 8, 9, 10, 11, 12, 13, 14
myAbc.someMethod(strs, true); //14, 13, 12, 11, 10, 5, 6, 7, 8, 9
}