Learn how to use Python’s optional type-hinting syntax to create cleaner and more useful code.

The pip3 reflects that I'm using Python 3, rather than Python 2. And the -U option indicates that I'd like to upgrade my installation of mypy, if the package has been updated since I last installed it ...

Ubuntu is a free computer system, like Windows or macOS, but it’s built by a community. It’s great for programmers because it’s very flexible and has lots of tools already built-in that help you code.