SSZ unify, it is better to use the newest geth SSZ lib

[GrapeBaBa]

This is the lib developed by Peter https://github.com/karalabe/ssz , we should check if go-ethereum has used it

[r4f4ss]

This is the lib developed by Peter https://github.com/karalabe/ssz , we should check if go-ethereum has used it

Geth does not use Karalabe SSZ implementation anyplace, as can be seen in go.mod file, it is not instaled in this project. I tried to search but I was not able to locate any discusion or PR to migrate to Karalabe implementation.

We should adapt Shisui to use whenever it is possible fastssz implementation, that is used by Geth.