public function is_rsvp_restricted( $event_id = null, $ticket_id = null, $user_id = null ) {
		// By default we always pass the current User
		if ( is_null( $user_id ) ) {
			$user_id = get_current_user_id();
		}

		/**
		 * Allow users to filter if this Event or Ticket has Restricted RSVP
		 *
		 * @param  boolean  $restricted Is this Event or Ticket Restricted?
		 * @param  int      $event_id   The Event/Post ID (optional)
		 * @param  int      $ticket_id  The Ticket/RSVP ID (optional)
		 * @param  int      $user_id    An User ID (optional)
		 */
		return apply_filters( 'event_tickets_is_rsvp_restricted', false, $event_id, $ticket_id, $user_id );
	}