UTF-8 String Indexing Strategies
It's a good article, but it would be nice if he'd also covered the Python 3 C API anti-pattern: forcing strings to be utf-8.  This means that you have latent bugs in your code. Notably when trying to treat all filenames as strings, sooner or later your code will explode when it meets someone's filesystem which has ancient Latin1 filenames.  Also when dealing with unfiltered user input.(And to head off replies - yes I understand you can "just do X" where "X" is some complicated thing to avoid the bug if you remember to do "X" beforehand)