code: def test_iterate_training_data_multiple_times(self):
      train = self.data.train
      data = list(train)
      data2 = list(train)
      self.assertEqual(10, len(data))
      self.assertEqual(10, len(data2))
      example = next(iter(data2))
      self.assertEqual(2, len(example))
      self.assertEqual({"label", "text"}, set(example))
  
imports: import unittest
  from typing import List
  from pytext.data.sources.data_source import SafeFileWrapper
  from pytext.data.sources.tsv import BlockShardedTSVDataSource, SessionTSVDataSource, TSVDataSource
  from pytext.utils.test import import_tests_module
label_desc: Use image node_id 8 for calling the TSVDataSourceTest obj's underlying member method code with example usage: obj.test_iterate_training_data_multiple_times() without return types