code: def RegisterTextKey(cls, key, frameid):
          
          def getter(id3, key):
              return list(id3[frameid])
  
          def setter(id3, key, value):
              try:
                  frame = id3[frameid]
              except KeyError:
                  id3.add(mutagen.id3.Frames[frameid](encoding=3, text=value))
              else:
                  frame.encoding = 3
                  frame.text = value
  
          def deleter(id3, key):
              del(id3[frameid])
  
          cls.RegisterKey(key, getter, setter, deleter)
docs: Register a text key.
  
          If the key you need to register is a simple one-to-one mapping
          of ID3 frame name to EasyID3 key, then you can use this
          function::
  
              EasyID3.RegisterTextKey("title", "TIT2")