`tf.keras.optimizers.schedules.CosineDecay`
        and`tf.keras.optimizers.schedules.CosineDecayRestarts`.

*   `tf.data`:

    *   Exposing `tf.data.experimental.ExternalStatePolicy`, which can be used
        to control how external state should be handled during dataset
        serialization or iterator checkpointing.
    *   Changing `tf.data.experimental.save` to store the type specification of