I have used id() in production code, but the circumstances were extremely specific: It was in some monitoring-related code that was trying to dig down into the guts of the interpreter for the purposes of tracking memory usage on the level of individual pages. It was a whole thing.
Which is to say: Users of Python almost certainly don't want to call id(), unless they are mucking around with something related to the functioning of the interpreter itself. The only other circumstance in which I've used it in anything like real code was in a quick hack where what I really wanted was to put a bunch of dicts in a set, but you can't do that, so I made a set of their IDs instead (but this wasn't in what I would call "production code").
In general, most of the "wtfs" listed here are pretty banal. If you're using `is` on immutable objects, you're basically just asking for trouble. The functioning of string and integer interning and constant folding are implementation curiosities, and if you ever write code in which such differences matter, then you have made an error.
Which is to say: Users of Python almost certainly don't want to call id(), unless they are mucking around with something related to the functioning of the interpreter itself. The only other circumstance in which I've used it in anything like real code was in a quick hack where what I really wanted was to put a bunch of dicts in a set, but you can't do that, so I made a set of their IDs instead (but this wasn't in what I would call "production code").
In general, most of the "wtfs" listed here are pretty banal. If you're using `is` on immutable objects, you're basically just asking for trouble. The functioning of string and integer interning and constant folding are implementation curiosities, and if you ever write code in which such differences matter, then you have made an error.