code: def maybe_download_and_extract(dest_directory, cifar_classnum):
      
      assert cifar_classnum == 10 or cifar_classnum == 100
      if cifar_classnum == 10:
          cifar_foldername = 'cifar-10-batches-py'
      else:
          cifar_foldername = 'cifar-100-python'
      if os.path.isdir(os.path.join(dest_directory, cifar_foldername)):
          logger.info("Found cifar{} data in {}.".format(cifar_classnum, dest_directory))
          return
      else:
          DATA_URL = DATA_URL_CIFAR_10 if cifar_classnum == 10 else DATA_URL_CIFAR_100
          filename = DATA_URL[0].split('/')[-1]
          filepath = os.path.join(dest_directory, filename)
          download(DATA_URL[0], dest_directory, expect_size=DATA_URL[1])
          tarfile.open(filepath, 'r:gz').extractall(dest_directory)
docs: Download and extract the tarball from Alex's website. Copied from tensorflow example