r = f
			}
			if strings.HasSuffix(file, ".zip") {
				zr, err := zip.NewReader(r.(io.ReaderAt), sz)
				if err != nil {
					return err
				}
				for _, file := range zr.File {
					if !file.FileInfo().IsDir() && strings.HasSuffix(file.Name, "xl.meta") {
						r, err := file.Open()
						if err != nil {
							return err
						}
						// Quote string...
						b, _ := json.Marshal(file.Name)