Here's a neat trick with `async let` I didn't realize. You can use it to avoid blocking on synchronous work.
@mattiem Do you (currently) get the same behaviour by pushing the decode behind an async function?
Cause async is implicitly nonisolated for the time being?

@rhysmorgan yes you do!

And there is a very significant advantage to doing it that way. Because the function signature is under your control, you can do use a `sending` return and avoid needing Sendable types.