code: function process_response(raw_response) {
                      const { item_preparer, query_result_preparer } = params;
                      const raw_data = raw_response.data;
                      if (Array.isArray(raw_data)) {
                          return resolve_promise(raw_data.map(item_preparer));
                      } else if (raw_data instanceof Query_result) {
                          const query_result = new Query_result(raw_data);
                          query_result.items = raw_data.items
                              .map(query_result_preparer)
                              ; // eslint-disable-line indent
                          return resolve_promise(query_result);
                      }
                      return resolve_promise(item_preparer(raw_data));
                  }
docs: -----------