public function verify($amount, $authority)
    {
        // backward compatibility
        if (count(func_get_args()) == 3) {
            $amount = func_get_arg(1);
            $authority = func_get_arg(2);
        }

        $inputs = [
            'MerchantID' => $this->merchantID,
            'Authority'  => $authority,
            'Amount'     => $amount,
        ];

        return $this->driver->verifyWithExtra($inputs);
    }