/**
  * Determine whether CT with given ID exists.
  *
  * @param int $ct_id ID of the CT to check.
  *
  * @return bool True if post with given ID exists and if it's a CT.
  */
 public static function is_valid( $ct_id ) {
     /* Note: This should not cause a redundant database query. Post objects are cached by WP core, so this one was
      * either already loaded or it has to be loaded now and will be reused in the future. */
     return WPV_Content_Template_Embedded::is_wppost_ct( WP_Post::get_instance( $ct_id ) );
 }