code: def test_tokenizer_add_token_chars(self):
      tokenizer = self.tokenizer_class.from_pretrained(
          "facebook/wav2vec2-base-960h"
      )
  
      # check adding a single token
      tokenizer.add_tokens("x")
      token_ids = tokenizer("C x A").input_ids
      self.assertEqual(token_ids, [19, 4, 32, 4, 7])
  
      tokenizer.add_tokens(["a", "b", "c"])
      token_ids = tokenizer("C a A c").input_ids
      self.assertEqual(token_ids, [19, 4, 33, 4, 7, 4, 35])
  
      tokenizer.add_tokens(["a", "b", "c"])
      token_ids = tokenizer("CaA c").input_ids
      self.assertEqual(token_ids, [19, 33, 7, 4, 35])
  
imports: import inspect
  import json
  import os
  import random
  import shutil
  import tempfile
  import unittest
  import numpy
  from transformers import WAV_2_VEC_2_PRETRAINED_MODEL_ARCHIVE_LIST, Wav2Vec2Config, Wav2Vec2CTCTokenizer, Wav2Vec2Tokenizer
  from transformers.models.wav2vec2.tokenization_wav2vec2 import VOCAB_FILES_NAMES, Wav2Vec2CTCTokenizerOutput
  from transformers.testing_utils import require_torch, slow
  from ...test_tokenization_common import TokenizerTesterMixin
label_desc: Use image node_id 3 for calling the Wav2Vec2CTCTokenizerTest obj's underlying member method code with example usage: obj.test_tokenizer_add_token_chars() without return types