class_docstr: **MNLI** 数据集的 **Loader**，如果您使用了这个数据，请引用
  
      https://www.nyu.edu/projects/bowman/multinli/paper.pdf
  
  读取的数据格式为::
  
      index   promptID        pairID  genre   sentence1_binary_parse  sentence2_binary_parse  sentence1_parse sentence2_parse sentence1       sentence2       label1  gold_label
      0       31193   31193n  government      ( ( Conceptually ( cream skimming ) ) ...
      1       101457  101457e telephone       ( you ( ( know ( during ( ( ( the season ) and ) ( i guess ) ) )...
      ...
  
  读取之后的 :class:`~fastNLP.core.DataSet` 中包含以下的内容： ``raw_words`` 是 ``sentence1`` ， ``raw_words2`` 是 ``sentence2`` ，
  ``target`` 是 ``gold_label``。测试集中没有 ``target`` 列。
  
  .. csv-table::
     :header: "raw_words1", "raw_words2", "target"
  
     "Conceptually cream ...", "Product and geography...", "neutral"
     "you know during the ...", "You lose the things to the...", "entailment"
     "...", "...", "..."
docstr: 自动下载数据集。
  
  :return: 数据集目录地址
docstr_tok: ["\u81ea\u52a8\u4e0b\u8f7d\u6570\u636e\u96c6\u3002",":","return",":","\u6570\u636e\u96c6\u76ee\u5f55\u5730\u5740"]
code: def download(self):
      r"""
      自动下载数据集。
  
      :return: 数据集目录地址
      """
      output_dir = self._get_dataset_path("mnli")
      return output_dir
  
imports: import os
  from typing import Union, Dict
  from .csv import CSVLoader
  from .json import JsonLoader
  from .loader import Loader
  from fastNLP.io.data_bundle import DataBundle
  from ..utils import check_loader_paths
  from fastNLP.core.dataset import DataSet, Instance
  from fastNLP.core.log import logger
label_desc: Use image node_id 4 for calling the MNLILoader obj's underlying member method code with example usage: obj.download() and returns: output_dir