Changes

Summary

1. merged
2. clarified management of interpreter threads: more generic; avoid interp.bind, which is unavailable in scala3;
3. clarified signature;
4. clarified signature;
5. clarified signature, based on hints by IntelliJ IDEA;
6. tuned signature;
7. more robust: avoid partiality;
8. tuned;
9. clarified signature;
10. clarified signature;
11. tuned --- avoid warnings in scala3;
12. clarified signature;