code: def test_transformation(self):
      special_sample = UTCnSample({"x": "", "y": "negative"})
      self.assertEqual([], trans_method.transform(special_sample))
  
      special_sample = UTCnSample(
          {"x": "~!@#$%^7890\"'", "y": "negative"}
      )
      self.assertEqual([], trans_method.transform(special_sample))
  
      random.seed(100)
      # test if the item change
      change_sample = trans_method.transform(sample, n=3)
      self.assertTrue(3 >= len(change_sample))
      # for s in change_sample:
      #     self.assertEqual(sample.get_tokens('x')[:1], s.get_tokens('x')[:1])
      #     self.assertEqual(sample.get_tokens('x')[-6:], s.get_tokens('x')[-6:])
      self.assertEqual(change_sample[0].get_value("x"), "叶学锋今天去金博威面试。")
  
imports: import random
  import unittest
  from textflint.input.component.sample import UTCnSample
  from textflint.generation.transformation.UTCN import CnSwapNamedEnt
label_desc: Use image node_id 1 for calling the TestSwapNamedEnt obj's underlying member method code with example usage: obj.test_transformation() without return types