private static @NotNull String reportResult(@NotNull Gens gens, @NotNull Differ differ, long startTime) {
    DateFormat formatter = new SimpleDateFormat("mm:ss");
    Date date = new Date((System.nanoTime() - startTime) / 1000000);
    return "Difference in spaces with the original:" + differ.getDifference(gens) + " Execution Time:" + formatter.format(date);
  }
private static @NotNull String reportResult(@NotNull Gens gens, @NotNull Differ differ, long startTime)