protected function registerVote (Vote $vote, $tag = null) : Vote
    {
        // Vote identifiant
        $vote->addTags($tag);
        
        // Register
        try {
            $vote->registerLink($this);
            $this->_Votes[] = $vote;
        } catch (CondorcetException $e) {
            // Security : Check if vote object not already register
            throw new CondorcetException(6,'Vote object already registred');
        }

        return $vote;
    }