public function addRole($role)
    {
        if (!$role instanceof Role) {
            //throw new \Exception( "addRole takes a Role object as the parameter" );
            $_role = new Role($role);
        } else {
            $_role = $role;
        }

        if (!$this->hasRole($_role->getRole())) {
            $_role->addUser($this);
            $this->roles->add($_role);
        }
    }