Mark Dickinson:
> I'd be happy to see `float.__setformat__` go, if it's not still needed for Python's test suite (which was its entire raison d'être). If no-one noticed the accidental misnaming, then it's pretty clear no-one's been using it.

Nobody noticed the since Python 3.7 (released in June 2018). Well, even test_float didn't use it :-D (I just fixed the typo yesterday.) So I expect that no one uses it.

> I'd like to bet that there are at least a few people out there using float.__getformat__, despite that its docstring says "You probably don't want to use this function".

Yeah, I changed my mind and I prefer to leave it unchanged for now. It doesn't prevent me to optimize _PyFloat_Pack8().