code: def _match_length(a: str, b: str) -> int:
      """
      需要把长度短的放在前面
  
      :param a:
      :param b:
      :return:
      """
      short = a if len(a) < len(b) else b
      long = a if len(a) >= len(b) else b
      match = SequenceMatcher(None, short, long).find_longest_match(
          0, len(short), 0, len(long)
      )
      return match.size
  
imports: from typing import Optional, Union, Tuple
  import os
  from fastNLP.core.log.logger import logger
  from difflib import SequenceMatcher
  from fastNLP.core.utils.utils import _get_fun_msg
label_desc: Use image node_id 2 for calling a global function with example usage: _match_length(a, b) and returns: match