code: def test_add_bos_token_slow(self):
      bos_token = "$$$"
      tokenizer = GPT2Tokenizer.from_pretrained(
          self.tmpdirname, bos_token=bos_token, add_bos_token=True
      )
  
      s = "This is a simple input"
      s2 = ["This is a simple input 1", "This is a simple input 2"]
  
      bos_token_id = tokenizer.bos_token_id
  
      out_s = tokenizer(s)
      out_s2 = tokenizer(s2)
  
      self.assertEqual(out_s.input_ids[0], bos_token_id)
      self.assertTrue(
          all(o[0] == bos_token_id for o in out_s2.input_ids)
      )
  
      decode_s = tokenizer.decode(out_s.input_ids)
      decode_s2 = tokenizer.batch_decode(out_s2.input_ids)
  
      self.assertTrue(decode_s.startswith(bos_token))
      self.assertTrue(all(d.startswith(bos_token) for d in decode_s2))
  
imports: import json
  import os
  import unittest
  from transformers import AutoTokenizer, GPT2Tokenizer, GPT2TokenizerFast
  from transformers.models.gpt2.tokenization_gpt2 import VOCAB_FILES_NAMES
  from transformers.testing_utils import require_jinja, require_tokenizers
  from ...test_tokenization_common import TokenizerTesterMixin
label_desc: Use image node_id 10 for calling the GPT2TokenizationTest obj's underlying member method code with example usage: obj.test_add_bos_token_slow() without return types