Please have a look at
https://hu.wikipedia.org/wiki/Szerkeszt%C5%91:BinBot/piroskat-userallap.py
Unfortunately, not all comments are in English, sorry for that.
def redCategories
shows how an HTML source can be downloaded and processed for red category
links. "(megíratlan szócikk)" after the title within brackets means
"unwritten article", I don't know the English phrase. "piros" in
comments
means red and "kék" means blue.