code: def __extract_tokens(s):
      sentence = []
      for item in s.split():
          tokens = item.split("_")
          tokens = [token for token in tokens if token]
          for i, token in enumerate(tokens):
              if i == 0:
                  sentence.append((token, "B-W"))
              else:
                  sentence.append((token, "I-W"))
      return sentence
  
file_path: underthesea/examples/pos_tag/data.py
imports: from os.path import join
label_desc: Use image node_id 3 for calling the WordTokenizeCorpusReader obj's underlying member method code with example usage: obj.__extract_tokens(s) and returns: sentence