If you would like to write Python 3 but need to maintain support for any particular version of Python 2, something that I can personally recommend is using the

If you would like to write Python 3 but need to maintain support for any particular version of Python 2, something that I can personally recommend is using the Coconut transpiler: http://coconut-lang.org/ http://coconut-lang.org/ The Coconut language is a superset of Python 3, so any valid Python 3 is valid Coconut. But the advantage of the transpiler extends beyond the language itself, in that it can target any version of Python from 2.6 onwards on the Python 2 branch and 3.2 onwards on the Python 3 branch. It has been really useful for me in that I want the advantages of type annotations and f-strings and other python 3.5+ features but I have to support running in an environment with only 2.6 installed. So when I target a 3.5+ version, all of those features are maintained, but when I target 2.6, the transpiler does all the work in converting to running 2.6 code for me.