code: def etag(self, etag):
          
          if etag is None:
              raise ValueError("Invalid value for `etag`, must not be `None`")
          if etag is not None and not re.search('[A-Za-z0-9]{0,256}', etag):
              raise ValueError("Invalid value for `etag`, must be a follow pattern or equal to `/[A-Za-z0-9]{0,256}/`")
  
          self._etag = etag
docs: Sets the etag of this BulkResponse.
          etag
  
          :param etag: The etag of this BulkResponse.
          :type: str