protected function getPersistentRoleScopeBy($role, Scope $scope = null) 
    {
        $em = $this->getDoctrine()->getManager();
        
        $roleScope = $em->getRepository('ChillMainBundle:RoleScope')
                ->findOneBy(array('role' => $role, 'scope' => $scope));
        
        if ($roleScope === NULL) {
            $roleScope = (new RoleScope())
                    ->setRole($role)
                    ->setScope($scope)
                    ;
            
            $em->persist($roleScope);
        }
        
        return $roleScope;
    }