code: def test_char_to_word(self, encodings):
      single, pair = encodings
  
      assert single.char_to_word(0) == 0
      assert single.char_to_word(1) == None
      assert pair.char_to_word(2) == 1
      assert pair.char_to_word(2, 0) == 1
      assert pair.char_to_word(2, 1) == None
      assert pair.char_to_word(3, 1) == 1
  
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 10 for calling the TestEncoding obj's underlying member method code with example usage: obj.test_char_to_word(encodings) without return types