Calls the callback functions that have been added to an action hook.

Processes the functions hooked into the ‘all’ hook.

Checks if a specific callback has been registered for this hook.

Checks if any callbacks have been registered for this hook.

Removes all callbacks from the current filter.

Removes a callback function from a filter hook.

Handles resetting callback priority keys mid-iteration.

Bridge to connect Requests internal hooks to WordPress actions.

Sets up Imagick for PDF processing.

List utility.