code: def test_gpt2(self):
      # test gtp 2
      score = GPT2Perplexity(ori_dataset, trans_dataset, "x").score
      real_score = [1.0, 1.0, 1.0, 0.591, 0.139]
      for i, j in zip(score, real_score):
          self.assertAlmostEqual(i, j, 3)
  
file_path: textflint/test/generation/validator/test_validator.py
imports: import unittest
  from textflint.input.component.sample.sa_sample import *
  from textflint.generation.validator.max_words_perturbed import MaxWordsPerturbed
  from textflint.generation.validator.edit_distance import EditDistance
  from textflint.generation.validator.translate_score import TranslateScore
  from textflint.generation.validator.gpt2_perplexity import GPT2Perplexity
  from textflint.input.dataset.dataset import Dataset
label_desc: Use image node_id 5 for calling the TestValidator obj's underlying member method code with example usage: obj.test_gpt2() without return types