code: def groupby(self, values):
          
  
          # TODO: if we are a MultiIndex, we can do better
          # that converting to tuples
          if isinstance(values, ABCMultiIndex):
              values = values.values
          values = ensure_categorical(values)
          result = values._reverse_indexer()
  
          # map to the label
          result = {k: self.take(v) for k, v in result.items()}
  
          return result
docs: Group the index labels by a given array of values.
  
          Parameters
          ----------
          values : array
              Values used to determine the groups.
  
          Returns
          -------
          groups : dict
              {group name -> group labels}