public static function decline_contact_request(int $userid, int $requesteduserid) {
        global $DB;

        if ($request = $DB->get_record('message_contact_requests', ['userid' => $userid,
                'requesteduserid' => $requesteduserid])) {
            $DB->delete_records('message_contact_requests', ['id' => $request->id]);
        }
    }