code: def split_by_idxs(self, train_idx, valid_idx):
          "Split the data between `train_idx` and `valid_idx`."
          return self.split_by_list(self[train_idx], self[valid_idx]f split_by_idxs(self, train_idx, valid_idx):
          "Split the data between `train_idx` and `valid_idx`."
          return self.split_by_list(self[train_idx], self[valid_idx])
docs: Split the data between `train_idx` and `valid_idx`.