transform(value: any, args?: any): any {
  // 4.1
  const hours = Math.floor((value / 60) / 60);
  const minutes = Math.floor(value / 60) % 60;
  const seconds = value % 60;
  return `${this.padding(hours)}${hours}:${this.padding(minutes)}${minutes}:${this.padding(seconds)}${seconds}`;
  // END 4.1
}

private padding(time) {
  return time < 10 ? '0' : '';
}