def add(map, use_offsets=true)
      raise ArgumentError, 'XmlSitemap::Map object required!' unless map.kind_of?(XmlSitemap::Map)
      raise ArgumentError, 'Map is empty!' if map.empty?
      
      @maps << {
        :loc     => use_offsets ? map.index_url(@offsets[map.group], @secure) : map.plain_index_url(@secure),
        :lastmod => map.created_at.utc.iso8601
      }
      @offsets[map.group] += 1
    end
def add(map, use_offsets=true)
      raise ArgumentError, 'XmlSitemap::Map object required!' unless map.kind_of?(XmlSitemap::Map)
      raise ArgumentError, 'Map is empty!' if map.empty?
      
      @maps << {
        :loc     => use_offsets ? map.index_url(@offsets[map.group], @secure) : map.plain_index_url(@secure),
        :lastmod => map.created_at.utc.iso8601
      }
      @offsets[map.group] += 1
    end
Initialize a new Index instance

 opts   - Index options

 opts[:secure] - Force HTTPS for all items. (default: false)

 Add map object to index

 map - XmlSitemap::Map instance