Install Python 3.7 (and IDLE3) on Ubuntu 19.10

This post show how to install Python 3.7 and IDLE (the integrated development environment for Python) on Ubuntu 19.10. Tested on VirtualBox running over Windows 10.

By default, Python 3 is installed on Ubuntu 19.10, currently Python 3.7.5rc1. You can run the command to install it if it's not installed:
$ sudo apt install python3

To run Python 3, simple enter the command:
$ python3

But IDLE is not installed by default. To install it, enter the command:
$ sudo apt install idle3

or

$ sudo apt-get install idle3

After installed, you can run IDLE with the command:
$ idle