Timber\URLHelper::is_internal_content PHP Method

    private static function is_internal_content($url)
    {
        // using content_url() instead of site_url or home_url is IMPORTANT
        // otherwise you run into errors with sites that:
        // 1. use WPML plugin
        // 2. or redefine content directory
        $is_content_url = strstr($url, content_url());
        // this case covers when the upload directory has been redefined
        $upload_dir = wp_upload_dir();
        $is_upload_url = strstr($url, $upload_dir['baseurl']);
        return $is_content_url || $is_upload_url;
    }