code: def test_label(self):
      # NliLength only add a sentence to hypothesis, which will
      # not change the label
      trans = nli_length.transform(sample1)
      self.assertEqual(sample1.y.field_value, trans[0].y.field_value)
  
file_path: textflint/test/generation/transformation/NLI/test_add_sent.py
imports: import unittest
  from textflint.input.component.sample.nli_sample import NLISample
  from textflint.generation.transformation.NLI import AddSent
label_desc: Use image node_id 2 for calling the TestNliLength obj's underlying member method code with example usage: obj.test_label() without return types