std::unique_ptr<TFE_Op, decltype(&TFE_DeleteOp)> reused_op(
      TFE_NewOp(context.get(), "Identity", status.get()), TFE_DeleteOp);
  TFE_OpReset(reused_op.get(), "Identity", custom_device_name, status.get());
  ASSERT_TRUE(TF_GetCode(status.get()) == TF_OK) << TF_Message(status.get());
  ASSERT_EQ(tensorflow::string(TFE_OpGetDevice(reused_op.get(), status.get())),
            tensorflow::string(custom_device_name));

    *   Added Adafactor optimizer `tf.keras.optimizers.Adafactor`.
    *   Added `warmstart_embedding_matrix` to `tf.keras.utils`.
        This utility can be used to warmstart an embeddings matrix so you
        reuse previously-learned word embeddings when working with a new set
        of words which may include previously unseen words (the embedding
        vectors for unseen words will be randomly initialized).

*   `tf.Variable`: