code: def get_iterator(self, data, axis=0):
          
          splitter = self._get_splitter(data, axis=axis)
          keys = self._get_group_keys()
          for key, (i, group) in zip(keys, splitter):
              yield key, group
docs: Groupby iterator
  
          Returns
          -------
          Generator yielding sequence of (name, subsetted object)
          for each group