def months_to_seconds(base)
      month_base = base.nil? ? nil : base + years.to_seconds(base)
      months.to_seconds(month_base)
    end
def months_to_seconds(base)
      month_base = base.nil? ? nil : base + years.to_seconds(base)
      months.to_seconds(month_base)
    end
Changes the base to compute the months for the right base year