Earlier quoted context omitted.
" but the interview engine is already running at full speed:" I dont know if this is a recent thing, but I had a similar thing where an interviewer was racing forward, and would only accept the answers he had in mind. In Python, he asked me how to search for substring. I was thinking but he started hurrying me. So I said regex and started writing a regex. "No, there is an inbuilt method" I couldnt remember the method…
I’d call this an understandable mistake on the part of the interviewer. “in” is a pretty commonly used operator. But it is also a bit unusual/trivial, in the sense that most languages would have a method or a function instead. It’s the sort of thing where if you’ve written, like, any Python at all, it’ll be somewhere in the back of your head. It’d surface immediately on the job. But if you’d been using any other lang…
Maybe this was a very junior position, but I'm with the interviewer here. Using regex would be very questionable - and a solid case of 1171.