plain/map
mapDatesInRange: Return an array of ISO PlainDate strings betweenstartDateandendDateinclusive.mapDaysInMonth: Return an array of ISO PlainDate strings for every day in the given year-month.
mapDatesInRange: Return an array of ISO PlainDate strings between startDate and endDate inclusive.mapDaysInMonth: Return an array of ISO PlainDate strings for every day in the given year-month.