def render
      xml = Builder::XmlMarkup.new(:indent => 2)
      xml.instruct!(:xml, :version => '1.0', :encoding => 'UTF-8')
      xml.sitemapindex(XmlSitemap::INDEX_SCHEMA_OPTIONS) { |s|
        @maps.each do |item|
          s.sitemap do |m|
            m.loc        item[:loc]
            m.lastmod    item[:lastmod]
          end
        end
      }.to_s
    end
def render
      xml = Builder::XmlMarkup.new(:indent => 2)
      xml.instruct!(:xml, :version => '1.0', :encoding => 'UTF-8')
      xml.sitemapindex(XmlSitemap::INDEX_SCHEMA_OPTIONS) { |s|
        @maps.each do |item|
          s.sitemap do |m|
            m.loc        item[:loc]
            m.lastmod    item[:lastmod]
          end
        end
      }.to_s
    end
Generate sitemap XML index