Based on a GitHub comment by @namn refering to Guido's email: https://mail.python.org/pipermail/python-dev/2014-April/134187.html
This is a harmless change under Python 2 (with a small performace hit) but means the code does not need alteration under Python 3. These changes were suggested by the 2to3 dict fixer but manually reviewed.
…ms (e.g. Python 3.2)
…assert_ method is deprecated in Python 2.7
… default (w+b) seems fine.
…imic assertTrue which was only added in Python 2.4+ and thus fails on Python 2.3 (see dev mailing list)
will pick them up.
…nd other minor changes
not "Nexus\f1.nex" to match the expected test output.