code: def from_music_service(cls, music_service, content_dict):
          
          # Form the item_id
          quoted_id = quote_url(content_dict['id'].encode('utf-8'))
          # The hex prefix remains a mistery for now
          item_id = '0fffffff{}'.format(quoted_id)
          # Form the uri
          is_track = cls == get_class('MediaMetadataTrack')
          uri = form_uri(item_id, music_service, is_track)
          # Form resources and get desc
          resources = [DidlResource(uri=uri, protocol_info="DUMMY")]
          desc = music_service.desc
          return cls(item_id, desc, resources, uri, content_dict,
                     music_service=music_service)
docs: Return an element instantiated from the information that a music
          service has (alternative constructor)
  
          Args:
              music_service (MusicService): The music service that content_dict
                  originated from
              content_dict (OrderedDict): The data to instantiate the music
                  service item from
  
          Returns:
              MusicServiceItem: A MusicServiceItem instance