code: def test_transformation(self):
      trans_sample = swap_ins.transform(sample)
      self.assertTrue(1 == len(trans_sample))
      trans_sample = trans_sample[0]
      self.assertEqual("小明想看一看书", trans_sample.get_value("x"))
      self.assertEqual(
          ["B", "E", "S", "B", "M", "M", "E"],
          trans_sample.get_value("y"),
      )
      self.assertEqual([0, 0, 0, 2, 2, 2, 0], trans_sample.mask)
  
imports: import unittest
  from textflint.generation.transformation.CWS.swap_verb import SwapVerb
  from textflint.input.component.sample.cws_sample import CWSSample
label_desc: Use image node_id 1 for calling the TestSwapVerb obj's underlying member method code with example usage: obj.test_transformation() without return types