The problem is that you define the function without calling it. Add
main()
after to call / invoke the function.
By the way, there's probably not much reason to use an old book. I'd recommend
Think CS as a great tutorial, but if it doesn't suit your taste then I recommend
our tutorials section.
The only thing I recommend you avoid is "Learn Python the Hard Way." I like the title in theory but the author, to put it as nicely as possible, is known to put his foot in his mouth and it can be extremely confusing / misleading for new programmers.