code: def test_locale(self):
      labels = metadata_writer.Labels()
  
      # Add from file.
      en_filepath = self.create_tempfile().full_path
      with open(en_filepath, "w") as f:
          f.write("a\nb")
      labels.add_from_file(en_filepath, "en")
  
      # Customized file name.
      labels.add(["A", "B"], "fr", exported_filename="my_file.txt")
      self.assertEqual(
          labels._labels,
          [
              metadata_writer.LabelItem(
                  "labels_en.txt", ["a", "b"], "en"
              ),
              metadata_writer.LabelItem(
                  "my_file.txt", ["A", "B"], "fr"
              ),
          ],
      )
  
imports: import os
  import tempfile
  from absl.testing import absltest
  from mediapipe.tasks.metadata import metadata_schema_py_generated
  from mediapipe.tasks.python.metadata.metadata_writers import metadata_info
  from mediapipe.tasks.python.metadata.metadata_writers import metadata_writer
  from mediapipe.tasks.python.test import test_utils
label_desc: Use image node_id 2 for calling the LabelsTest obj's underlying member method code with example usage: obj.test_locale() without return types