code: def ds_list(self):      # NOTE: how to name to distinguish from locally configured datastream objects?
          
          # FIXME: how to make access to a versioned ds_list ?
  
          if self._ds_list is None:
              self._ds_list = self._get_datastreams()
          return self._ds_list
docs: Dictionary of all datastreams that belong to this object in Fedora.
          Key is datastream id, value is an :class:`ObjectDatastream` for that
          datastream.
  
          Only retrieved when requested; cached after first retrieval.