Lunar constructor
Implementation
Lunar(DateTime dateTime,
{int? lunarYear, int? lunarMonth, int? lunarDay, bool? isLeap}) {
this._dateTime = dateTime;
this.lunarYear = lunarYear ?? 0;
this.lunarMonth = lunarMonth ?? 1;
this.lunarDay = lunarDay ?? 1;
this.isLeap = isLeap == null ? false : isLeap;
}