docs: def _rel(self, copy=False):
          """
          Get descriptive kwargs of the container (e.g. name, description, meta).
          """
          rel = {}
          for key, obj in vars(self).items():
              if not isinstance(obj, (pd.Series, pd.DataFrame, pd.SparseSeries, pd.SparseDataFrame)) and not key.startswith('_'):
                  if copy and 'id' not in key:
                      rel[key] = deepcopy(obj)
                  else:
                      rel[key] = obj
          return rel