code: def test_label(self):
      # NLIAntonymSwap will change some word to its opposite meaning,
      # which leads contradiction label
      trans = nli_antonymswap.transform(sample1)
      self.assertEqual("contradiction", trans[0].y.field_value)
  
imports: import unittest
  from textflint.input.component.sample.nli_sample import NLISample
  from textflint.generation.transformation.NLI import SwapAnt
label_desc: Use image node_id 2 for calling the TestNliSwapAnt obj's underlying member method code with example usage: obj.test_label() without return types