code: def test_PrefixSwap(self):
      # test data with no words with prefix or postfix
      data = POSSample({"x": ["is"] * 3, "y": ["O"] * 3})
      self.assertEqual([], swap_ins.transform(data))
  
      # test faction
      change = swap_ins.transform(data_sample, n=3)
      self.assertTrue(3 == len(change))
      for item in change:
          for ori_word, trans_word, mask in zip(
              data_sample.get_words("x"),
              item.get_words("x"),
              item.get_mask("x"),
          ):
              self.assertTrue(
                  ori_word == trans_word
                  if mask == 0
                  else ori_word != trans_word
              )
  
imports: import unittest
  from textflint.generation.transformation.POS.prefix_swap import SwapPrefix
  from textflint.input.component.sample.pos_sample import *
label_desc: Use image node_id 1 for calling the TestPrefixSwap obj's underlying member method code with example usage: obj.test_PrefixSwap() without return types