Your shim layer would have to make assumptions on the encoding of your strings, which can lead to nasty bugs. And also handle reading from files correctly, or

Your shim layer would have to make assumptions on the encoding of your strings, which can lead to nasty bugs. And also handle reading from files correctly, or list file names from the os, or anything that communicates outside of the python interpreter. The main reason why python 3 was created was to manage these complexities, and even then some people[1] say it wasn't done properly. [1] http://lucumr.pocoo.org/2014/5/12/everything-about-unicode/ http://lucumr.pocoo.org/2014/5/12/everything-about-unicode/