code: def text_to_words(review_text):
      letters_only = re.sub("[^a-zA-Z]", " ", review_text)
      words = letters_only.lower().split()
      return words
  
file_path: BigDL/python/dllib/src/bigdl/dllib/models/textclassifier/textclassifier.py
imports: import itertools
  import re
  from optparse import OptionParser
  from bigdl.dllib.feature.dataset import news20
  from bigdl.dllib.nn.layer import *
  from bigdl.dllib.nn.criterion import *
  from bigdl.dllib.optim.optimizer import *
  from bigdl.dllib.utils.common import *
  from bigdl.dllib.nncontext import *
  from bigdl.dllib.utils.utils import detect_conda_env_name
  import os
  import datetime
  from bigdl.dllib.utils.log4Error import *
label_desc: Use image node_id 1 for calling a global function with example usage: text_to_words(review_text) and returns: words