docs: def utf8_normalize(input_filename, comment_char='#', to_upper=False):
      """Normalize UTF-8 characters of a file
      """
      # Prepare the input dictionary file in UTF-8 and NFC
      temp_dict_fd, output_filename = tempfile.mkstemp()
  
      logging.debug('to_nfc from file {} to file {}'.format(input_filename, output_filename))
  
      with codecs.open(output_filename, 'w', 'utf-8') as f:
          with codecs.open(input_filename, 'r', 'utf-8') as input_f:
              lines = sorted([unicodedata.normalize(UTF8_NORMALIZATION, l)
                              for l in input_f.readlines()
                              if not l.strip().startswith(comment_char)])
              if to_upper:
                  lines = [l.upper() for l in lines]
  
              f.writelines(lines)
  
      return output_filename