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 language earlier that day, it might not pop up reflexively, or in interview-stress mode.
It’s essentially trivia, and over-indexing on trivia is a mistake. But if they were a Python writer every day, I could see why they’d incorrectly expect everybody to have “in” in their l1 cache.
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 language earlier that day, it might not pop up reflexively, or in interview-stress mode.
It’s essentially trivia, and over-indexing on trivia is a mistake. But if they were a Python writer every day, I could see why they’d incorrectly expect everybody to have “in” in their l1 cache.