public function exec()
    {
        if (true === $this->multi) {
            $ret         = array();
            $this->multi = false;
            // exec
            foreach ($this->execList as $todos) {
                $redis = $todos[0]['redis']; // ^^ not so secure ?
                $this->notifyEvent('multi', array());
                $redis->multi();
                foreach ($todos as $todo) {
                    if ($todo['function'] instanceof \Closure) {
                        $ret[] = $todo['function']($redis);
                    } else {
                        throw new Exception("Ce n'est pas une Closure !");
                    }
                }
                $this->notifyEvent('exec', array());
                $redis->exec();
            }
            $this->execList = array(); // purge the execList

            return $ret;
        } else {
            throw new Exception("you have to call multi before exec");
        }
    }