@staticmethod
    def cost(target, output):
        raise NotImplementedError()
Add the given ``tracks`` to playlist at the given ``index``.
dataset/ETHPy150Open lisa-lab/pylearn2/pylearn2/costs/autoencoder.py/GSNFriendlyCost.cost--crossover with--dataset/ETHPy150Open mopidy/pyspotify/spotify/playlist.py/Playlist.add_tracks