docs: def rename_index(self, *args):
          '''change the index name(s).
  
          * call with one argument:
              1. list of new index names (to replace all old names)
  
          * call with two arguments:
              1. old index name(s) (or index/indices)
              2. new index name(s)
          '''
          if len(args) == 1:
              new_indices = args[0]
              old_indices =force_list(self.indices.keys())
          else:
              old_indices, new_indices = args
              old_indices, single = convert_index_to_keys(self.indices, old_indices)
              if single:
                  old_indices, new_indices = [old_indices], [new_indices]
  
          if len(new_indices) != len(old_indices):
              raise ValueError('Length of update indices (%s) does not match '
                               'existing indices (%s)' %
                               (len(new_indices), len(old_indices)))
  
          map(MI_check_index_name, new_indices)
  
          if len(new_indices) != len(set(new_indices)):
              raise ValueError('New indices names are not unique: %s' % (new_indices,))
  
          od_replace_key(self.indices, old_indices, new_indices, multi=True)