public function getRoleParents($role, $onlyParents = true) {
        $parents = array();
        if (Zend_Registry::isRegistered('Zend_Acl')) {
            $acl = Zend_Registry::get('Zend_Acl');
            $roles = $acl->getRoles();

            foreach ($roles as $potentialParent) {
                if ($acl->inheritsRole($role, $potentialParent, $onlyParents)) {
                    $parents[] = $potentialParent;
                }
            }
        }
        return $parents;
    }