The assertion is also not necessarily accurate. Python 2 & 3 are included on Ubuntu 14.04 (and maybe earlier). My understanding is that different system tools r

The assertion is also not necessarily accurate. Python 2 & 3 are included on Ubuntu 14.04 (and maybe earlier). My understanding is that different system tools require different versions. Python 2 is /usr/bin/python Python 3 is /usr/bin/python If on Windows and you have both python 2.7 and python 3.x installed, just just use the py command to automatically select the correct runtime. I think you may need to specify the shabang for this to work (i.e. "#!/usr/bin/env python" for a 2.x script and "#!/usr/bin/env python3" for a 3.x script). Despite some recent discussions lamenting slow adoptions, everyone I know and myself write all new code in 3.5.x and only fall back to 2.7 for legacy code or when you need a module that is not yet 3.x compatible. Problem is I work at a small company with about 10 devs. If a 2.x script works, we have zero incentive to port it to 3.x because we have such a huge backlog of work items.