public function merchantByCurrency($config = array(), $currency = '')
    {
        if (!is_array($config)) {
            $this->errorMessage[] = 'config is not array!';
            return false;
        } elseif (count($config) == 0) {
            $this->errorMessage[] = 'Empty config array!';
            return false;
        }

        $config['CURRENCY'] = str_replace(' ', '', $currency);
        $variables = array('MERCHANT', 'SECRET_KEY');

        foreach ($variables as $var) {
            if (isset($config[$currency . '_' . $var])) {
                $config[$var] = str_replace(' ', '', $config[$currency . '_' . $var]);
            } elseif (!isset($config[$currency . '_' . $var])) {
                $config[$var] = 'MISSING_' . $var;
                $this->errorMessage[] = 'Missing ' . $var;
            }
        }

        if ($this->debug) {
            foreach ($config as $configKey => $configValue) {
                if (strpos($configKey, 'SECRET_KEY') !== true) {
                    $this->debugMessage[] = $configKey . '=' . $configValue;
                }
            }
        }
        return $config;
    }