I think the desire to make this one line ruined any chance of someone easily understanding this solution. I don't think there's any harm in expanding some lines for readability and maintainability.

This was a literal challenge I was given in an interview. I would say it's much easier with someone to talk it over with (your evaluator) and even if you can't solve it perfectly, be sure to articulate your thought process and communicate each step of the process out loud and you should be fine. Technical challenges are more to hear your thought process when faced with an unfamiliar and difficult problem than it is about getting strictly to the 'right' answers.

Hey guys, I'm preparing for interview questions and I'm struggling at kyu 4. In terms of codewar kyu problem ranks, how hard are interview questions?

@kazk That's a great point. Do you see better benchmarks from has_key? as well?

I like your solution with case :)