Alan Du

ParallelMapper missing a `worker_init_fn`

1

### 🚀 The feature Add `worker_init_fn` support for `ParallelMapper` (and maybe `persistent_workers`). ### Motivation, pitch Right now, there is no way to specify a custom `worker_init_fn` for the parallel mapping...

This improves the type annotations bundled with `imageio`. These are meant to fix some of the type errors I was hitting in our internal codebase after upgrading `imageio` and is...