code: def setUpClass(cls):
      cls.save_root = os.path.join(os.path.dirname(__file__), "data")
      cls.preprocessor_file = os.path.join(
          cls.save_root, "preprocessor.pkl"
      )
      if not os.path.exists(cls.save_root):
          os.mkdir(cls.save_root)
      if os.path.exists(cls.preprocessor_file):
          os.remove(cls.preprocessor_file)
  
imports: import os
  import shutil
  import unittest
  import numpy
  from anago.preprocessing import IndexTransformer, pad_nested_sequences
label_desc: Use image node_id 2 for calling the TestIndexTransformer obj's underlying member method code with example usage: obj.setUpClass(cls) without return types