The crux of the problem, that Python 2 handles unicode/bytes/text in a non-intuitive way, isn't surprising. However, the way the author set up the problem and

The crux of the problem, that Python 2 handles unicode/bytes/text in a non-intuitive way, isn't surprising. However, the way the author set up the problem and walked through the context, test failure, diagnosis and resolution was great. Always pleasant to find a coding post-mortem written as well as this one.