code: def parse_sent(sent):
      """Sentence preprocessor."""
      res = re.sub("[^a-zA-Z]", " ", sent)
      res = res.strip().lower().split()
      return res
  
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 12 for calling a global function with example usage: parse_sent(sent) and returns: res