This is Chimera, Arachne's abstract data access layer.
This repository is not yet ready for public consumption. Many key elements will change before Arachne is ready to be used, even just for experimentation.
The repository has been made public so people can follow the development process, and to make CI integration easier, but it would be foolish and counterproductive to try to actually use it, or even play around with it just yet.
Stay tuned for this warning to disappear, then have at it :)