public function get_item_download_url($download_id)
{
$order = $this->get_order();
return $order ? add_query_arg(array('download_file' => $this->get_variation_id() ? $this->get_variation_id() : $this->get_product_id(), 'order' => $order->get_order_key(), 'email' => urlencode($order->get_billing_email()), 'key' => $download_id), trailingslashit(home_url())) : '';
}