code: def test_save_dataclass_objs_to_headered_csv(self):
      dataclass_objs = [
          TestDataclass2("a", 1),
          TestDataclass2("a", 2),
          TestDataclass2("b", 3),
      ]
  
      with tempfile.TemporaryDirectory(
          prefix=f"{TestDataUtils}"
      ) as tempdir:
          csv_file_name = Path(tempdir) / "data.csv"
          save_dataclass_objs_to_headered_csv(
              dataclass_objs, csv_file_name
          )
          with open(csv_file_name) as f:
              lines = list(f.readlines())
              self.assertEqual(len(lines), 4)
              self.assertEqual(lines[0], "a,b\n")
              self.assertEqual(lines[1], "a,1\n")
              self.assertEqual(lines[2], "a,2\n")
              self.assertEqual(lines[3], "b,3\n")
  
imports: import os
  import tempfile
  import unittest
  import unittest.mock
  from dataclasses import dataclass
  from pathlib import Path
  from pytorchvideo.data.utils import DataclassFieldCaster, export_video_array, load_dataclass_dict_from_csv, save_dataclass_objs_to_headered_csv
  from pytorchvideo.data.video import VideoPathHandler
  from utils import temp_encoded_video
label_desc: Use image node_id 7 for calling the TestDataUtils obj's underlying member method code with example usage: obj.test_save_dataclass_objs_to_headered_csv() without return types