Need to create a file that contains blocked zones only.
The reason for this is that Pi-Hole's gravity filters cannot block a zone (at least, not via lists - you can add regex's manually), only exact domain names.
That's fairly inflexible when ad-flingers can register foo.com and then just cycle through subdomains.
So, want to dump out a file of unbound format zone blocks - I have unbound upstream of Pi-hole, so zone blocks can happen there.
That way, we can do things like ensure 2o7.net is blocked so that anything CNAMEing to subdomains of it are automatically blocked