code: def test_load(self):
      for loader in [
          YelpFullLoader,
          YelpPolarityLoader,
          IMDBLoader,
          SST2Loader,
          SSTLoader,
          ChnSentiCorpLoader,
      ]:
          data_bundle = loader().load()
          print(data_bundle)
  
file_path: fastNLP/tests/io/loader/test_classification_loader.py
imports: import os
  import pytest
  from fastNLP.io import DataBundle
  from fastNLP.io.loader.classification import YelpFullLoader, YelpPolarityLoader, IMDBLoader, SSTLoader, SST2Loader, ChnSentiCorpLoader, THUCNewsLoader, WeiboSenti100kLoader, MRLoader, R8Loader, R52Loader, OhsumedLoader, NG20Loader
label_desc: Use image node_id 2 for calling the TestDownload obj's underlying member method code with example usage: obj.test_load() without return types