Piwik\Plugins\UsersManager\API::checkAccessType PHP Method

    private function checkAccessType($access)
    {
        $accessList = Access::getListAccess();
        // do not allow to set the superUser access
        unset($accessList[array_search("superuser", $accessList)]);
        if (!in_array($access, $accessList)) {
            throw new Exception(Piwik::translate("UsersManager_ExceptionAccessValues", implode(", ", $accessList)));
        }
    }