Upgrade Python from 2.7 to 3.5 under Ubuntu

Download the latest Python with code in Ubuntu terminal

sudo apt-get install Python3

You will be prompted to enter the Linux password, enter the password and download
The Python program that you just downloaded is installed in usr/local/lib/python3.5

Delete the default Python link file under the usr/bin/directory with a command

Establish a new connection to the system default Python compiler

sudo ln-s/usr/bin/python3.5/usr/bin/python

Verify that the system default Python is the one you just installed

Enter Python directly in the command window

Upgrade Python from 2.7 to 3.5 under Ubuntu