public function setMatchMax($matchMax)
    {
        if (is_int($matchMax) === true && $matchMax >= 0) {
            $this->matchMax = $matchMax;
        } else {
            $msg = "The 'matchMax' argument must be a positive integer, '" . gettype($matchMax) . "' given.";
            throw new InvalidArgumentException($msg);
        }
    }