This is a WordPress plugin that contains several example custom transformers for the [WordPress ActivityPub plugin](https://wordpress.org/plugins/activitypub/). It works like an add-on for it.
Note that this plugin does not yet work with the latest release of the ActivityPub plugin. A pull request is already open: https://github.com/Automattic/wordpress-activitypub/pull/569
But if you want to test it you likely need the latest development branch of the ActivityPub plugin which you can find here: https://code.event-federation.eu/Event-Federation/wordpress-activitypub/src/branch/dev/extendable-transformers