    # File lib/action_view/helpers/asset_tag_helper.rb, line 162
          def auto_discovery_link_tag(type = :rss, url_options = {}, tag_options = {})
            tag(
              "link",
              "rel"   => tag_options[:rel] || "alternate",
              "type"  => tag_options[:type] || Mime::Type.lookup_by_extension(type.to_s).to_s,
              "title" => tag_options[:title] || type.to_s.upcase,
              "href"  => url_options.is_a?(Hash) ? url_for(url_options.merge(:only_path => false)) : url_options
            )
          end