docs: public static String toTimecode(long duration, TimeUnit units) {
      // FIXME Negative durations are also supported.
      // https://www.ffmpeg.org/ffmpeg-utils.html#Time-duration
      checkArgument(duration >= 0, "duration must be positive");
  
      long nanoseconds = units.toNanos(duration); // TODO This will clip at Long.MAX_VALUE
      long seconds = units.toSeconds(duration);
      long ns = nanoseconds - SECONDS.toNanos(seconds);
  
      long minutes = SECONDS.toMinutes(seconds);
      seconds -= MINUTES.toSeconds(minutes);
  
      long hours = MINUTES.toHours(minutes);
      minutes -= HOURS.toMinutes(hours);
  
      if (ns == 0) {
        return String.format("%02d:%02d:%02d", hours, minutes, seconds);
      }
  
      return ZERO.trimTrailingFrom(String.format("%02d:%02d:%02d.%09d", hours, minutes, seconds, ns));
    }