I created par-iter crate at https://github.com/dudykr/ddbase/tree/583980a9bd9b77c3c9a3c7a2fb360e4f71a65258/crates/par-iter because I need to switch parallelism library depending on the target binary and target platform. For Wasm, I want it to be sequential. So I forked rayon to allow switching underlying parallelism library, but I want to check if the rayon team is open to a PR to allow switching it directly from rayon.

e.g.

• cargo feature chili: Use chili instead of rayon_core for parallelism. (I need the heartbeat scheduling algorithm for SWC)
• cargo feature no-parallelism: Use single core with best effort basis. (In my case, it's only for Wasm target)