Sorry for all the comments, but this guy gets it.

I love open-ended questions like that because you can go into any direction where the candidate reveals strength.

A favorite programming language question of mine starts, "Talk to me about containers in [your favorite language] - a container is an object that holds other objects." And then of course a lot of prompts and leading questions from me. I'm not aiming at any specific answer, but I am interested in going as deeply as I can, hearing about their favorite container or clever containers they have used or built and why they might choose one over another.