docstr: Test if the v-head has the correct shape
docstr_tok: ["Test","if","the","v-head","has","the","correct","shape"]
code: def test_value_head_shape(self):
      r"""
      Test if the v-head has the correct shape
      """
      for model_name in self.all_model_names:
          model = self.trl_model_class.from_pretrained(model_name)
          self.assertTrue(model.v_head.summary.weight.shape[0] == 1)
  
imports: import gc
  import tempfile
  import unittest
  import torch
  from transformers import AutoModel, AutoModelForCausalLM, AutoModelForSeq2SeqLM
  from trl import AutoModelForCausalLMWithValueHead, AutoModelForSeq2SeqLMWithValueHead, create_reference_model
label_desc: Use image node_id 2 for calling the VHeadModelTester obj's underlying member method code with example usage: obj.test_value_head_shape() without return types