it's not documented how to run the unit tests, so if one sees a failing / erroneous test, there's some uncertainty whether one has run them in the right way.
running "nosetests" from the top directory seems to work.
but running "nosetests --with-doctest" gives lots of errors and failures (for python 2.7).
while trying to fix some of them, I noticed that there might be an issue with python2 vs. python3 and that tuning the doctests to work for python2 AND 3 might be a rather tedious job.
are the doctests only expected to work for python3?
shall they get migrated to separate tests?