Working on a Backdrop port of your module

Problem/Motivation

I wanted to be able to add ISBN-based nodes to a site that I have already upgraded to Backdrop, so I came to this module to see if I could leverage it. I was able to get it working on an old copy of my site running D7, after updating the code to match the new API and some PHP 8.x changes as well.

Now I am able to run it on Backdrop as well.

Thank you for writing this module.