public static function getPurifierInstance($configName = 'default')
    {
        $_this = Purifier::getInstance();

        if (!isset($_this->_instances[$configName])) {
            if (!isset($_this->_configs[$configName])) {
                throw new \InvalidArgumentException(sprintf('Configuration and instance `%s` does not exist!', $configName));
            }
            $_this->_instances[$configName] = new \HTMLPurifier($_this->_configs[$configName]);
        }

        return $_this->_instances[$configName];
    }