Doctest fails in Python 3

The library is behaving correctly but we cannot distinguish between unicode and str literals...

Ideas?

https://dirkjan.ochtman.nl/writing/2014/07/06/single-source-python-23-doctests.html

http://www.georgevreilly.com/blog/2016/04/05/DoctestsUnicodeLiteralsPython2_3Compat.html

Another solution would be to move away from doctest...