public function limit($pNb)
    {
        if (is_array($pNb) and count($pNb) == 2 and isset($pNb[0])
            and isset($pNb[1]) and is_int($pNb[0]) and is_int($pNb[1])) {
            $nb = $pNb[1];
            $this->skip($pNb[0]);
        } else if (is_int($pNb)) {
            $nb = $pNb;
        } else {
            throw new Exception("Validation failed for type 'array' or 'int'");
        }

        $this->_limit = $nb;
        return $this;
    }