In this first recipe, we will briefly cover a transverse and kind of a prosaic subject: Python 2 or Python 3?

Python 3 has been available since 2008, but many Python users are still stuck with Python 2. By improving many aspects of Python 2, Python 3 has broken compatibility with the previous branch. Migrating to Python 3 may therefore require a significant investment.

Even if there aren't that many compatibility-breaking changes, a program that works perfectly fine in Python 2 may not work at all in Python 3. For example, your very first Hello World Python 2 program doesn't work anymore in Python 3; print "Hello World!" raises a SyntaxError in Python 3. Indeed, print is now a function rather than a statement. You should write print("Hello World!"), which also works fine in Python 2.

Whether you start a new project or need to maintain an old Python library, the question of choosing between Python 2 and Python 3 arises. Here, we give some arguments...