code: def test_special_tokens_mask_input_pairs_and_bos_token(self):
      # TODO: change to self.get_tokenizers() when the fast version is implemented
      tokenizers = [
          self.get_tokenizer(do_lower_case=False, add_bos_token=True)
      ]
      for tokenizer in tokenizers:
          with self.subTest(f"{tokenizer.__class__.__name__}"):
              sequence_0 = "Encode this."
              sequence_1 = "This one too please."
              encoded_sequence = tokenizer.encode(
                  sequence_0, add_special_tokens=False
              )
              encoded_sequence += tokenizer.encode(
                  sequence_1, add_special_tokens=False
              )
              encoded_sequence_dict = tokenizer.encode_plus(
                  sequence_0,
                  sequence_1,
                  add_special_tokens=True,
                  return_special_tokens_mask=True,
              )
              encoded_sequence_w_special = encoded_sequence_dict[
                  "input_ids"
              ]
              special_tokens_mask = encoded_sequence_dict[
                  "special_tokens_mask"
              ]
              self.assertEqual(
                  len(special_tokens_mask),
                  len(encoded_sequence_w_special),
              )
  
              filtered_sequence = [
                  (x if not special_tokens_mask[i] else None)
                  for i, x in enumerate(encoded_sequence_w_special)
              ]
              filtered_sequence = [
                  x for x in filtered_sequence if x is not None
              ]
              self.assertEqual(encoded_sequence, filtered_sequence)
  
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_tokenizers
  from ...test_tokenization_common import TokenizerTesterMixin
label_desc: Use image node_id 12 for calling the GPT2TokenizationTest obj's underlying member method code with example usage: obj.test_special_tokens_mask_input_pairs_and_bos_token() without return types