I'd like a small Python package, `scheduler`, that runs tasks on a schedule — some
things need to happen every so often, others at particular times of day, and I want
one place to register that work and have it actually fire when it's supposed to.

The picture in my head is: I describe a handful of tasks, say when each one should
run, hand the lot to the scheduler, and let it tick along firing them at the right
moments. The kind of thing you'd reach for to send a nightly report, refresh a cache
every few minutes, do the weekly cleanup — ordinary recurring chores, nothing exotic.

What I care about most is that it's pleasant to register a task and say when it runs,
and that I can trust the timing — when a task was due, it ran, and I can tell that it
did. It should be importable as `scheduler`, and there should be an obvious way to
actually start the thing going, whether that's from code or the command line; use
your judgment.

Beyond that the design is yours. Keep it small and lean on the standard library where
you can — I'd rather see the choices you'd actually defend than a wall of options or
configuration. Some real tests around the scheduling behavior would give me
confidence it does what you think it does, and a couple of examples in a README so I
can see how it's meant to be used. Clean and well-thought-through beats sprawling.
