code: def test_multi_corpus_sampled_dataset_uniform_sample(self):
      self._test_sample_helper(
          expected_sample_from_first_ds_percentage=0.5
      )
  
file_path: fairseq/tests/test_multi_corpus_sampled_dataset.py
imports: import unittest
  from collections import OrderedDict
  import numpy
  import torch
  from fairseq.data import LanguagePairDataset, TokenBlockDataset
  from fairseq.data.multi_corpus_sampled_dataset import MultiCorpusSampledDataset
  from tests.test_train import mock_dict
label_desc: Use image node_id 3 for calling the TestMultiCorpusSampledDataset obj's underlying member method code with example usage: obj.test_multi_corpus_sampled_dataset_uniform_sample() without return types