Python finally offloads some batteries

> Most python packages only support of subset of python reasons for lots of good reasons.

In my experience, this "subset" is usually of the form "version 3.x or later" for some value of x (or, for a handful of very old libraries, "version 2.7.x only"). I don't believe I have seen a whole lot of libraries that set a maximum version, other than the ones which were never ported to 3.