After a lot of trial and error, I upgraded my system's default version of Python on Ubuntu. The debian_defaults file was part of the solution on Linux.
Now I am trying to do the same thing on my Mac... I downloaded and installed Python with the correct $ commands, and now I have to (before a few other commands) change the version argument in debian_defaults...
The problem is, there is not a debian_defaults on a Mac, and there is not even a Python folder on Mac... Where is the equivalent file on Mac where I can set the version of Python?