public static function clean_data($user) {
        if (empty($user)) {
            return $user;
        }

        foreach ($user as $field => $value) {
            // Get the property parameter type and do the cleaning.
            try {
                $user->$field = core_user::clean_field($value, $field);
            } catch (coding_exception $e) {
                debugging("The property '$field' could not be cleaned.", DEBUG_DEVELOPER);
            }
        }

        return $user;
    }