lookup method
Implementation
@override
CalendarValueLookup lookup(int year, [int? month, int? day]) {
DateTime current = DateTime(year, month ?? 1, day ?? 1);
if (dates.any((element) => _convertNecessarry(element, year, month, day)
.isAtSameMomentAs(current))) {
return CalendarValueLookup.selected;
}
return CalendarValueLookup.none;
}