And you work full time as a software engineer, or some other role? Honestly blown away if you work as a programmer that this sort of request would require looking at documentation.
If you have just started your career and are full invested in 1 or 2 programming languages, sure this may sound alien to you.
If your interviewer finds that problematic, well, that's on them.
So, the equivalent of creating a dictionary, yeah, sure. But there's loads and loads of stuff that I only use maybe once a week (and someone else maybe uses daily) and that I'd have to awkwardly Google (I use Kagi btw) even during an interview.
Your interviewer is probably also questioning if it's (a, e) or (e, a), but you passed the fraud filter.