code: def test_get_labels(self):
      a = download_nouns_mapping()
      self.assertEqual(1000, len(a))
      self.assertEqual(a["n03887697"], "paper_towel")
  
file_path: petastorm/examples/imagenet/tests/test_generate_imagenet_dataset.py
imports: import os
  import shutil
  import tempfile
  import unittest
  import cv2
  import numpy
  from examples.imagenet.generate_petastorm_imagenet import download_nouns_mapping, imagenet_directory_to_petastorm_dataset
label_desc: Use image node_id 3 for calling the TestGenerate obj's underlying member method code with example usage: obj.test_get_labels() without return types