function __construct($post_type = 'pack', $meta = array())
 {
     $this->post_type = $post_type;
     $this->option_name = 'payment_package';
     // backend text
     $this->localize = array('backend_text' => array('text' => __('%s for %d days', 'aecore-class-ae-package-backend'), 'data' => array('et_price', 'et_number_posts')));
     $this->meta = array_merge($meta, array('sku', 'et_price', 'et_number_posts', 'order', 'option_name', 'et_duration', 'et_featured', 'et_not_duration'));
     $this->convert = array('post_title', 'post_name', 'post_content', 'post_excerpt', 'post_author', 'post_status', 'ID', 'post_type');
     self::$instance = $this;
 }