code: def playlists(self):
          
          if self._playlists is None:
              playlists_data = self._api.user_playlists(self.identifier)
              playlists = []
              for playlist_data in playlists_data:
                  playlist = _deserialize(playlist_data, PlaylistSchema)
                  playlists.append(playlist)
              self._playlists = playlists
          return self._playlists
docs: 获取用户创建的歌单
  
          如果不是用户本人，则不能获取用户默认精选集