code: def rename(self, name_dict=None, inplace=None, **names):
          
          # TODO: add separate rename_vars and rename_dims methods.
          inplace = _check_inplace(inplace)
          name_dict = either_dict_or_kwargs(name_dict, names, 'rename')
          for k, v in name_dict.items():
              if k not in self and k not in self.dims:
                  raise ValueError("cannot rename %r because it is not a "
                                   "variable or dimension in this dataset" % k)
  
          variables, coord_names, dims, indexes = self._rename_all(
              name_dict=name_dict, dim_dict=name_dict)
          return self._replace(variables, coord_names, dims=dims,
                               indexes=indexes, inplace=inplace)
docs: Returns a new object with renamed variables and dimensions.
  
          Parameters
          ----------
          name_dict : dict-like, optional
              Dictionary whose keys are current variable or dimension names and
              whose values are the desired names.
          inplace : bool, optional
              If True, rename variables and dimensions in-place. Otherwise,
              return a new dataset object.
          **names, optional
              Keyword form of ``name_dict``.
              One of name_dict or names must be provided.
  
          Returns
          -------
          renamed : Dataset
              Dataset with renamed variables and dimensions.
  
          See Also
          --------
          Dataset.swap_dims
          DataArray.rename