int $post_ID, WP_Post $post_after, WP_Post $post_before )
Fires once an existing post has been updated.
Use this hook whenever you need to compare values before and after the post update.
This hook runs after the database update.
This hook pass up to 3 arguments, as follows:
$post_after(post object after the update);
$post_before(post object before the update);