There are still a bunch of things that are not implemented yet, so
not sure whether to remove them and add them later. Or keep them,
and modify/delete them later.
This is commit c3ead6d48cc2431d72ae7f81947df7fa5fefa92b in
https://github.com/bolt/bolt
Copied on 2018-10-30 14:00
Once Query works, it could be refactored from `Bolt\Storage\Query`
to `Bolt\Query`