docs: def wrap(self, data, many):
          """Wrap response in envelope."""
          if not many:
              return data
          else:
              data = {'parts': data}
              multipart = self.context.get('multipart')
              if multipart:
                  data.update(MultipartObjectSchema(context={
                      'bucket': multipart.bucket}).dump(multipart).data)
              return data