class_docstr: 提供给 ``OneflowDataLoader`` 使用的 warp 类，其功能是对 dataset 进行封装，wrap 修改 dataset 的 __getitem__ 函数，增加返回
  数据的下标 idx 。
  
  ..note::
  
      需要注意的是传入 ``__init__`` 的 dataset 需要实现 __getattribute__ 方法才能在 _FDataset 实例化对象中调用 dataset 的方法
class_docstr_tok: ["\u63d0\u4f9b\u7ed9","``","OneflowDataLoader","``","\u4f7f\u7528\u7684","warp","\u7c7b\uff0c\u5176\u529f\u80fd\u662f\u5bf9","dataset","\u8fdb\u884c\u5c01\u88c5\uff0cwrap","\u4fee\u6539","dataset","\u7684","__getitem__","\u51fd\u6570\uff0c\u589e\u52a0\u8fd4\u56de","\u6570\u636e\u7684\u4e0b\u6807","idx","\u3002","..","note",":",":","\u9700\u8981\u6ce8\u610f\u7684\u662f\u4f20\u5165","``","__init__","``","\u7684","dataset","\u9700\u8981\u5b9e\u73b0","__getattribute__","\u65b9\u6cd5\u624d\u80fd\u5728","_FDataset","\u5b9e\u4f8b\u5316\u5bf9\u8c61\u4e2d\u8c03\u7528","dataset","\u7684\u65b9\u6cd5"]
code: def __getitem__(self, item: Union[int, list]) -> Tuple:
      return (item, self.dataset[item])
  
imports: from typing import Optional, Callable, Sequence, Union, Tuple, Dict, Mapping, List, Any
  from abc import ABC
  from copy import deepcopy
  from fastNLP.core.dataset import DataSet
  from fastNLP.core.collators import Collator
  from fastNLP.core.dataloaders.utils import indice_collate_wrapper
  from fastNLP.envs.imports import _NEED_IMPORT_ONEFLOW
  from fastNLP.core.samplers import ReproducibleBatchSampler, ReproducibleSampler, UnrepeatedSampler, RandomSampler
  from ..utils import _match_param
  from ..utils import HasLenGetitemType
label_desc: Use image node_id 2 for calling the _FDataSet obj's underlying member method code with example usage: obj.__getitem__(item) and returns: item,  self