Back in uni we had an ad-hoc competition, throwing paper airplanes out of a 15th storey window, in calm weather. All sorts of designs were tried, flying time measured. Towards the end it occured to me to compare the times against an etalon: an unfolded A4 sheet. Dropped the sheet from the window, and it started the typical erratic descent of a falling leaf, swinging back-and-forth, pulling straight up at the end of the swings. It took twice as long to touch down than the next best airplane, so it pretty much instantly killed the competition.

Don't know about the rest of the 'Dive Into...' sites, but the world may be actually better off without the Python site, if we are to believe this blog:

"Beginners see this and think that Python is complex and hard when it's actually one of the few languages designed to be easy to use. It's a damn shame they run into this book first.
(...)
This is for a first program? When beginners are told "go read Dive Into Python" they run into examples like this and get discouraged. I could see if Mr. Pilgrim had a giant disclaimer or something warning people that this isn't a beginner's book, but he doesn't. In fact, he has a whole damn chapter on installing Python 3 as if it's for a beginner.

This book is so full of bad initial examples and difficult to follow instructions that it actually hurts Python to have it exist. When beginners stumble onto it they end up getting discouraged and go on to another language. I personally have had too many friends who are eager to learn programming find this festering dung pile before I could warn them and get turned off from programming.