code: def save_tag_to_audio_file(audio_file, tracklisting):
      
      print("Trying to tag {}".format(audio_file))
      f = mediafile.MediaFile(audio_file)
  
      if not f.lyrics:
          print("No tracklisting present. Creating lyrics tag.")
          f.lyrics = 'Tracklisting' + '\n' + tracklisting
      elif tracklisting not in f.lyrics:
          print("Appending tracklisting to existing lyrics tag.")
          f.lyrics = f.lyrics + '\n\n' + 'Tracklisting' + '\n' + tracklisting
      else:
          print("Tracklisting already present. Not modifying file.")
          raise TagNotNeededError
  
      f.save()
      print("Saved tag to file:", audio_file)
docs: Saves tag to audio file.