addDays method

@override Gregorian addDays(int days)

makes a new date object with added days to this date

Original date object remains unchanged

this Method is safe

Implementation

@override
Gregorian addDays(int days) {
  if (days == 0) {
    return this;
  } else {
    return Gregorian.fromJulianDayNumber(
      julianDayNumber + days,
      hour,
      minute,
      second,
      millisecond,
    );
  }
}