[nerdponx]

In this case the candidate evidently didn't understand it either, but was repeating a pattern they had seen before, which IMO is a form of anti-mastery: don't do things that you don't understand, especially when you're supposed to be demonstrating your skill and understanding.

[necovek]

Having a candidate understand all of the edge cases of a language syntax is a very high bar to clear: there is a lot of programmer between a "master" and "anti-master".

I've used Python for 20+ years, and while I'd confidently use a == b == c or 1 < a < 10, I didn't know the specifics and wouldn't use it in cases like 10 > a < 8 (or really, any other case chaining supports).

I believe myself to be an expert at Python and I'll explain differences between different loop types (while/for, ranges/iterators/generators, list comprehensions, functools, external C libraries like pandas or numpy), I think I wouldn't be confused only because I am aware I don't know the details and have a quick way to prove it works.

[nerdponx]

Maybe I interpreted the article differently than you did.

I got the impression that the candidate was repeating the x == y == z pattern because they'd seen it in other people's code and was pretty sure it worked, not because they knew about comparison chaining. At minimum I'd expect a candidate to be able to clarify that (x == y) == z is not the same thing, not just "idk it works whenever I do it". My reaction to that was: at some point, you do need to at least be able to reason about your own code.

In a more generous light, yes, I agree with everything you wrote. The precise details of comparison chaining are out of scope and I'm sure that most Python developers (myself included) don't know or remember them.

[necovek]

I agree that anyone (including an obviously juniorish candidate) using it should be able to explain it to an extent, but maybe not if you confidently and wrongly claim it doesn't work as an interviewer :)