code: def test_char_to_token(self, encodings):
      single, pair = encodings
  
      assert single.char_to_token(0) == 1
      assert pair.char_to_token(0) == 1
      assert pair.char_to_token(0, 0) == 1
      assert pair.char_to_token(1, 0) == None
      assert pair.char_to_token(0, 1) == 6
      assert pair.char_to_token(2, 1) == None
  
file_path: hf-tokenizers/bindings/python/tests/bindings/test_encoding.py
imports: import pytest
  from tokenizers import BertWordPieceTokenizer
  from ..utils import bert_files, data_dir
label_desc: Use image node_id 9 for calling the TestEncoding obj's underlying member method code with example usage: obj.test_char_to_token(encodings) without return types