docs: def serialize(self, content):
          """ Serialize to xml.
  
          :return string:
  
          """
          return self.xmldoc_tpl % (
              'true' if self.response.status_code == HTTP_200_OK else 'false',
              str(self.resource.api or ''),
              int(mktime(datetime.now().timetuple())),
              super(XMLTemplateEmitter, self).serialize(content)
          )