code: def tearDown(self):
      global MNIST_DOWNLOAD_METHOD
      if MNIST_DOWNLOAD_METHOD is not None:
          mnist_download.get_mnist_dataset = MNIST_DOWNLOAD_METHOD
          mnist_benchmark.get_mnist_dataset = MNIST_DOWNLOAD_METHOD
  
          MNIST_DOWNLOAD_METHOD = None
  
file_path: avalanche/tests/benchmarks/classic/test_mnist_benckmarks.py
imports: import unittest
  import avalanche.benchmarks.datasets.external_datasets.mnist
  import avalanche.benchmarks.classic.cmnist
  from avalanche.benchmarks import PermutedMNIST, ClassificationExperience, RotatedMNIST, SplitMNIST
  from tests.unit_tests_utils import load_experience_train_eval, FAST_TEST, is_github_action
label_desc: Use image node_id 2 for calling the MNISTBenchmarksTests obj's underlying member method code with example usage: obj.tearDown() without return types