public function placeholder($config = null): string
    {
        $config = array_merge($this->defaults, $config ?? []);

        switch ($config['type']) {
            case 'svg':
                return $this->placeholderSVG($config);
            case 'gif':
                return $this->placeholderGIF($config);
            case 'silhouette':
                return $this->placeholderSilhuette($config);
        }

        return '';
    }