Obtains the month-of-year which is the specified number of months after this one.
Obtains the month-of-year which is the specified number of months before this one.
Obtains a MonthDay by combining this month with the specified day-of-month.
Obtains a MonthDay by combining this month with the specified day-of-month.
if the day-of-month is invalid for the month.
(richMonth: any2stringadd[RichMonth]).+(other)
Enriches a Month with additional methods.