import of ttk

[Verde Denim]

In reading through one of the learning articles, I have a bit of code
that imports ttk, but I apparently don't have this installed. I've
looked up the svn checkout for python-tk, and have checked it out
(read-only), but still get the same error. I'm running 2.6.6 python, if
that helps. The article I'm looking at is here -
http://www.zetcode.com/gui/tkinter/introduction/

Any input is appreciated.