I just installed another instance of Ubuntu 16-server and ran into some problems upgrading Python. It turns out, the former mainstay of Python repo has shut it down to protect abuse. Ooops, never knew.
Here is an alternative method tho to get it up and running:
Python 3.6 happens to be in the reverse repository of Ubuntu 16, so you can just run : "sudo apt-get install python3.6" without any issues.
For earlier versions of Ubuntu: 14.04....16.04 these work:
sudo add-apt-repository ppa:deadsnakes/ppa
sudo apt-get update
sudo apt-get install python3.6
