`SerializationContext` argument to enable overriding the default policy
        for the handling external state during iterator checkpointing. This is
        not a backwards compatible change and all subclasses of `IteratorBase`
        *need to be updated* accordingly.
*   `tf.keras`
    *   Add a new `BackupAndRestore` callback for handling distributed training
        failures & restarts. Please take a look at this