public function api($name)
    {
        switch ($name) {
            case 'actress':
                $api = new Apis\Actress($this->client, $this->credential);
                break;
            case 'author':
                $api = new Apis\Author($this->client, $this->credential);
                break;
            case 'floor':
                $api = new Apis\Floor($this->client, $this->credential);
                break;
            case 'genre':
                $api = new Apis\Genre($this->client, $this->credential);
                break;
            case 'maker':
                $api = new Apis\Maker($this->client, $this->credential);
                break;
            case 'product':
                $api = new Apis\Product($this->client, $this->credential);
                break;
            case 'series':
                $api = new Apis\Series($this->client, $this->credential);
                break;
            default:
                throw new InvalidArgumentException(sprintf('Undefined api instance called: "%s"', $name));
                break;
        }
        return $api;
    }