Yeah, a lot of places use it as an initial phone-screen "can you code" question. I did bust out a version on one call which did detection of combining classes,

Yeah, a lot of places use it as an initial phone-screen "can you code" question. I did bust out a version on one call which did detection of combining classes, normalized into composed form before checking the reverse, etc., and the interviewer seemed kinda lost as I explained it. Ended up not working for them, but for different reasons.