Method: Edit Post handler function.
Source Files: includes/admin/class-learndash-admin-posts-edit.php
Method: Called from WP at the start of the post edit
Method: Called from WP when saving a post edit form. This filter allows us to interject a ‘currentTab’ query string variable.
Method: Filter post_parent before update/insert. Ensure the post_parent field is zero for course post types.