code: def random_string(string_length):
      """Random string generator for unmatched captions."""
      letters = string.ascii_lowercase
      return "".join(
          random.choice(letters) for i in range(string_length)
      )
  
imports: import collections
  import logging
  import random
  import re
  import string
  import numpy
  from scenic.projects.vid2seq.metrics.cider import Cider
  from scenic.projects.vid2seq.metrics.meteor import Meteor
  from scenic.projects.vid2seq.metrics.ptbtokenizer import PTBTokenizer
label_desc: Use image node_id 3 for calling a global function with example usage: random_string(string_length) and returns: str