I've found generators to be a great way to keep separate concerns separate. Now you can have a function whose job is to figure out what the next thing is, then consume it eslewhere as a simple sequence.

In the past I'd have a function accept a `visit(x)` callback, but then I had to invent a protocol for error handling and early cancellation between the host and callback.

The ability to just `yield x` and have done with it is a breath of fresh air.