code: func (d Datastore) DownloadFile(ctx context.Context, path string, file string, param *soap.Download) error {
  	u, p, err := d.downloadTicket(ctx, path, param)
  	if err != nil {
  		return err
  	}
  	return d.Client().DownloadFile(ctx, file, u, p)
  }
docs: // DownloadFile via soap.Download with an http service ticket