Well, I wrote it for myself during Starwars III. Not easily, but I learnt something. Nice conversation with myself. :-) I don't understand, why are there only some special pages in wikipedia.py while others are not.
I have read wikipedia.py, and I found that class Site has some methods for reading special pages, but not for all of them! I need Special:WantedCategories which is not listed there. Please help!