python3 upgrade ubuntu code example

Example 1: ubuntu install python

# first do:
sudo apt-get update
# after do:
sudo apt-get install python3.6
# then it should be installed

Example 2: update python ubuntu

sudo apt-get update && sudo apt-get upgrade
sudo apt-get install python3.7

Example 3: update ubuntu to python 3.85

sudo update-alternatives --config python3