code: def test_multi_corpus_dataset(self):
      for distribution in [
          [0.5, 0.5],
          [0.1, 0.9],
          [0.9, 0.1],
          [0.0, 1.0],
      ]:
          self._test_sample_helper(distribution=distribution)
  
file_path: fairseq/tests/test_multi_corpus_dataset.py
imports: import unittest
  from collections import OrderedDict
  import torch
  from fairseq.data import LanguagePairDataset, TokenBlockDataset
  from fairseq.data.multi_corpus_dataset import MultiCorpusDataset
  from tests.test_train import mock_dict
label_desc: Use image node_id 3 for calling the TestMultiCorpusDataset obj's underlying member method code with example usage: obj.test_multi_corpus_dataset() without return types