#include <JeeLib.h;>
What is the casino thing ? It looks like an abandoned project that got web squatted / Brandjacked.
Source code: https://github.com/jeelabs/jeelib
Website: https://jeelabs.org/202x/sw/jeelib/
The latter redirects to a page that shows Git commits, but it's a hidden page in a Dutch site about online casinos. It does look a bit shady. In the GitHub org of jeelabs, there are only two authors and neither seem to be based in the Netherlands.
Here's an archived website that documents the jeelib library.
Relevant line:
> a Sleepy class for ultra low-power sleeping of ATmega and ATtiny µC’s
From a quick skimming of the codebase, I couldn't find this class. If I were the author, I would have forked the Sleepy class for my own use.
Edit: Here's the definition of the Sleepy class.
https://github.com/jeelabs/jeelib/blob/6df2d8da785aca77790e9...
It uses avr-libc's sleep functions.
> <avr/sleep.h>: Power Management and Sleep Modes
https://www.nongnu.org/avr-libc/user-manual/group__avr__slee...
He did a series of posts as he made it ever more power efficient, but that was about 10 years ago.