multiple of the number of replicas.
    *   `tf.data.Dataset` now supports automatic data distribution and sharding
        in distributed environments, including on TPU pods.
    *   Distribution policies for `tf.data.Dataset` can now be tuned with 1.
        `tf.data.experimental.AutoShardPolicy(OFF, AUTO, FILE, DATA)` 2.
        `tf.data.experimental.ExternalStatePolicy(WARN, IGNORE, FAIL)`