Respect\Validation\Rules\CreditCard::__construct PHP Method

    public function __construct($brand = null)
    {
        if (null !== $brand && !isset($this->brands[$brand])) {
            $brands = implode(', ', array_keys($this->brands));
            $message = sprintf('"%s" is not a valid credit card brand (Available: %s).', $brand, $brands);
            throw new ComponentException($message);
        }
        $this->brand = $brand;
    }