/// <summary>
/// Factorial2s this instance.
/// </summary>
/// <remark>Author : PetterLiu 2009-03-29 11:28 http://wintersun.cnblogs.com </remark>
public void Factorial2()
{
var dd = Functional.Y <int, int>(h => m => (m == 1) ? 1 : h(m - 1) * m);
Console.WriteLine(dd(5));
}