Pull Request Template

Checklist

• [ x] Confirmed that run-checks all script has been executed.
• [ x] Made sure the book is up to date with changes in this PR.

Changes

Make param id public. This can help to setup custom optimizers (by splitting of gradients for a specific param), and has had some more requests..

This could also just be a getter, replacing the id seems a bit wild but might be valid for advanced use cases.

It's also already pseudo public, as it's possible to do something like

// read:
let (id, val) = param.comsume()
// "write":
let param = ParamID::new(id, val);