code: def test_get_transformations(self):
      self.assertTrue(
          ([[2, 4]], [["中央电视台"]], [["B", "M", "M", "M", "E"]])
          == swap_ins._get_transformations(data_sample.get_words())
      )
      self.assertRaises(
          AssertionError, swap_ins._get_transformations, sent1
      )
      self.assertRaises(
          AssertionError, swap_ins._get_transformations, ""
      )
      self.assertTrue(swap_ins._get_transformations([]) == ([], [], []))
  
imports: import unittest
  from textflint.generation.transformation.CWS.swap_contraction import SwapContraction
  from textflint.input.component.sample.cws_sample import CWSSample
label_desc: Use image node_id 1 for calling the TestSwapContraction obj's underlying member method code with example usage: obj.test_get_transformations() without return types