Given that it's trained on human code, your "a control variable which then isn't even used" probably needs an "anymore" added. I don't know about others, but that's a sin i committed many, many, many times: You try all kinds of stuff to get code working the way you want it right now(*), including adding all sorts of counters to support debug output. When the stuff finally works, you remove the prints, and then close the file as fast as possible. Leaving all the unused and dead code alone, because you don't want to break it again by accident.

(*) Friday evening. All coworkers have already gone home for the weekend. You are desperate to finish the current task any way possible so you can leave, too. There's always time to do a cleanup of the code next week, right?