public function getDriver()
    {
        if ($this->driver === null) {
            // Get driver configuration
            $config = $this->config('drivers.' . $this->config('driver'), []);

            // Get driver class
            $driver = Arr::pull($config, 'class');

            // Create driver instance
            $this->driver = new $driver($config);
        }

        return $this->driver;
    }