def days_in_month(month = self.month, year = self.year)
      (month == 12 && kabisa?(year) || month.odd?) ? 30 : 29
    end
def days_in_month(month = self.month, year = self.year)
      (month == 12 && kabisa?(year) || month.odd?) ? 30 : 29
    end
number of days in this (or the specified) month and year