def date_group_items=(options)
      options.each do |date_group|
        raise ArgumentError, "date_group_items should be an array of hashes specifying the options for each date_group_item" unless date_group.is_a?(Hash)
        date_group_items << DateGroupItem.new(date_group)
      end
    end
def date_group_items=(options)
      options.each do |date_group|
        raise ArgumentError, "date_group_items should be an array of hashes specifying the options for each date_group_item" unless date_group.is_a?(Hash)
        date_group_items << DateGroupItem.new(date_group)
      end
    end
Date group items are date group filter items where you specify the
 date_group and a value for that option as part of the auto_filter
 @note This can be specified, but will not be applied to the date
 values in your workbook at this time.