*   Adds a `save_traces` argument to `model.save`/ `tf.keras.models.save_model`
    which determines whether the SavedModel format stores the Keras model/layer
    call functions. The traced functions allow Keras to revive custom models and
    layers without the original class definition, but if this isn't required the
    tracing can be disabled with the added option.
*   The `tf.keras.mixed_precision` API is now non-experimental. The