They did change the API for Python modules implemented in C. That was actually part of the reason why the 2->3 transition went so badly. It wasn't realistic t

They did change the API for Python modules implemented in C. That was actually part of the reason why the 2->3 transition went so badly. It wasn't realistic to switch to 3.x when the libraries either weren't there or were a lot slower (due to using pure Python instead of C code). It also wasn't realistic to rewrite the libraries when the users weren't there. It was in many respects a perfect case study in how not to do version upgrades.