code: private static long append(
        @NonNull StringBuilder builder, long dividend, long divisor, @NonNull String unit) {
      if (dividend == 0 || dividend < divisor) {
        return dividend;
      }
      builder.append(dividend / divisor).append(unit);
      return dividend % divisor;
    }
docs: Appends the result of the division to the specified builder if the dividend is not zero.
  
  @param builder the builder to append to
  @param dividend the dividend
  @param divisor the divisor
  @param unit the time unit to append after the result of the division
  @return the remainder of the division