I spent a few minutes scanning the 'intro' pages. If there were any function examples there, I missed it/them. A simple example or five of what in the hell a f

I spent a few minutes scanning the 'intro' pages. If there were any function examples there, I missed it/them. A simple example or five of what in the hell a function can do might motivate some readers to want to dig deeper. I don't want to today.