code: def setUpClass(cls):
      # model_id
      cls.model_id = "trl-internal-testing/dummy-GPT2-correct-vocab"
  
      # get models and tokenizer
      cls.gpt2_model = (
          AutoModelForCausalLMWithValueHead.from_pretrained(
              cls.model_id
          )
      )
      cls.gpt2_tokenizer = AutoTokenizer.from_pretrained(cls.model_id)
      cls.gpt2_tokenizer.pad_token = cls.gpt2_tokenizer.eos_token
  
imports: import unittest
  from unittest.mock import patch
  import torch
  from transformers import AutoTokenizer
  from trl import AutoModelForCausalLMWithValueHead, TextEnvironment, TextHistory
label_desc: Use image node_id 1 for calling the TextEnvironmentTester obj's underlying member method code with example usage: obj.setUpClass(cls) without return types