code: def serialize(self, content):
          
          worker = XMLSerializer(
              scheme=self.resource,
              format=self.resource._meta.emit_format,
              options=self.resource._meta.emit_options,
              **self.resource._meta.emit_models
          )
          return self.xmldoc_tpl % (
              'true' if not self.response.error else 'false',
              str(self.resource.api or ''),
              int(mktime(datetime.now().timetuple())),
              worker.serialize(content)
          )
docs: Serialize to XML.
  
          :return string: serialized XML