Package Control is the Sublime Text package manager. It includes a list of over 2,500 packages available for install, and users can add any GitHub or BitBucket repository themselves. Once installed, packages are kept up-to-date automatically.
The example code creates the Installed Packages folder for you (if necessary), and then downloads the Package Control.sublime-package into it. The download will be done over HTTP instead of HTTPS due to Python standard library limitations, however the file will be validated using SHA-256.