# File lib_doc/rucy/lang.rb, line 97
    def filter_open(context, script_name, request, response, logger)
      if (request.has_header? 'Accept-Language') then
        if (lang_range = @lang_sel.select(request.header('Accept-Language'))) then
          response.status = @status
          response.set_header('Location', @location[lang_range])
          response.set_header('Content-Type', 'text/plain')
          response.absolute_location(request)
          response.start_body
          if (request.method != 'HEAD') then
            response << response.reason << "\n"
            response << "Jump to #{response.header('Location')}.\n"
          end
          terminate_filter
        end
      end
      nil
    end