`DYNAMIC` (equivalent to today's `"distributed_epoch"` mode), or one of
        the static sharding policies: `FILE`, `DATA`, `FILE_OR_DATA`, or `HINT`
        (corresponding to values of `tf.data.experimental.AutoShardPolicy`).

        Static sharding (auto-sharding) requires the number of tf.data service
        workers be fixed. Users need to specify the worker addresses in
        `tensorflow.data.experimental.DispatcherConfig`.