I'm working on a special-case compare function for bounded integers for the sort stuff. By looking at the implementation, I figured out that Py_SIZE of a long is the sign times the number of digits (...right?). Before looking at the implementation, though, I had looked for this info in the docs, and I couldn't find it anywhere. Since Py_SIZE is public, I think the documentation should make clear what it returns for PyLongs, for example somewhere on the "Integer Objects" page. Apologies if this is specified somewhere else in the docs and I just couldn't find it.