class_docstr: A base dummy tokenizer to derive from.
class_docstr_tok: ["A","base","dummy","tokenizer","to","derive","from","."]
docstr: Returns a signature for the tokenizer.
  :return: signature string
docstr_tok: ["Returns","a","signature","for","the","tokenizer",".",":","return",":","signature","string"]
code: def signature(self):
      """
      Returns a signature for the tokenizer.
      :return: signature string
      """
      return "none"
  
file_path: evaluate/metrics/google_bleu/tokenizer_13a.py
imports: import re
  from functools import lru_cache
label_desc: Use image node_id 1 for calling the BaseTokenizer obj's underlying member method code with example usage: obj.signature() and returns: str