Code that will break in Python 4
The whole Python versioning fiasco is simply baffling to me as an outsider.  Why not mark Python 3 modules with a tag, or different file extension, or anything, and require the Python 3 interpreter to be able to interpret Python 2 code as well as Python 3 code?This is e.g. how the (roughly analogous) split between C and C++ is handled, and it works fine for the most part.  No bizarre polyglot code games.Edit: Just to be clear, C++ is not a superset of C: http://stackoverflow.com/a/1201840/270610