code: def check_and_prepare_sentence(sentence):
      sentence = sentence.lower().replace("co2", "c o zwei")
      chars = []
      for c in sentence:
          if (
              CLI_ARGS.normalize
              and c not in "äöüß"
              and not in_alphabet(c)
          ):
              c = (
                  unicodedata.normalize("NFKD", c)
                  .encode("ascii", "ignore")
                  .decode("ascii", "ignore")
              )
          for sc in c:
              if not in_alphabet(c):
                  return None
              chars.append(sc)
      return validate_label("".join(chars))
  
file_path: DeepSpeech/bin/import_tuda.py
imports: import argparse
  import csv
  import os
  import tarfile
  import unicodedata
  import wave
  import xml.etree.ElementTree
  from collections import Counter
  import progressbar
  from deepspeech_training.util.downloader import SIMPLE_BAR, maybe_download
  from deepspeech_training.util.importers import validate_label_eng
  from ds_ctcdecoder import Alphabet
label_desc: Use image node_id 3 for calling a global function with example usage: check_and_prepare_sentence(sentence) and returns: validate_label, None