def diff_in_months(date2)
      if date2 > self
        ZDate.diff_in_months(month, year, date2.month, date2.year)
      else
        ZDate.diff_in_months(date2.month, date2.year, month, year) * -1
      end
    end
def diff_in_months(date2)
      if date2 > self
        ZDate.diff_in_months(month, year, date2.month, date2.year)
      else
        ZDate.diff_in_months(date2.month, date2.year, month, year) * -1
      end
    end
difference in months FROM self TO date2, for instance, if self is oct 1 and date2 is nov 14, will return 1
 if self is nov 14 and date2 is oct 1, will return -1