I'm thinking about asking a question for a customized data structure that would motivate creating an Iterator in Java. HNQ potential?

@BenI. You don't even need a data structure. An iterator can return values not stored (successive primes, for example). But you need to keep it in scope, of course. An edu question.

Or combine it with your induction idea. A recursive data generator implemented as an iterator.

@buffy How would that deal with a base case?

Also... what you just said sounds like the start of a great answer. HNQ potential, then?

Also, @GypsySpellweaver I still haven't forgotten about the convoluted code question. Perhaps my teaching style has changed, or perhaps I just have better students this year, but I haven't been seeing any of the sorts of convolutions I was talking about this year, so I still don't have a clear example.

@BenI. Put it in the sand box so I can think about it for a bit.

Done!