This is a demo showing how to write animations using coroutines in pogoscript.
A coroutine is a function that yields periodically, giving up control to the caller of the function. So if the function animates a sprite, yielding allows other sprites to animate themselves, and for those sprites to be drawn on the canvas.
Your brain will melt.
Because it might help you understand how continuations work.
In particular you probably want to read the animate firework object, the one containing all the calls to yield!.