I'm really confused by your comment.

"int being a function is really a CPython implementation detail"

I don't understand this. I should be able to do isinstance(x, int) in all implementations of Python, no? So `int` must be a class across all Python implementation, no?

"why would you want to consider the detail that it’s really a C function?"

I don't want to consider the detail that int is a C function, I thought that int is a class and expected it to be marked :class:`int` in the documentation.