code: def test_save_and_load(self):
      it = IndexTransformer(lower=False)
      x1, y1 = it.fit_transform(self.x, self.y)
      x1_word, x1_char = x1
  
      self.assertFalse(os.path.exists(self.preprocessor_file))
      it.save(self.preprocessor_file)
      self.assertTrue(os.path.exists(self.preprocessor_file))
  
      it = IndexTransformer.load(self.preprocessor_file)
      x2, y2 = it.transform(self.x, self.y)
      x2_word, x2_char = x2
  
      np.testing.assert_array_equal(x1_word, x2_word)
      np.testing.assert_array_equal(x1_char, x2_char)
      np.testing.assert_array_equal(y1, y2)
  
imports: import os
  import shutil
  import unittest
  import numpy
  from anago.preprocessing import IndexTransformer, pad_nested_sequences
label_desc: Use image node_id 13 for calling the TestIndexTransformer obj's underlying member method code with example usage: obj.test_save_and_load() without return types