def get_model_param_range_map(self, param):
        """
        Given a model param, get the index sub-range of the param that this
        data-parallel rank owns.
        """
        model_index, dtype = self.model_param_gbuf_map[param]
        gbuf_range_map = self.model_gbuf_ranges[model_index][dtype]
        param_range_map = gbuf_range_map["param_map"][param]
        return param_range_map

        Given a model param, get the index sub-range of the param that this
        data-parallel rank owns.
        
training/DeepSpeed-Domino/domino/optimizer/distrib_optimizer.py