// Return an identity op.
TFE_Op* IdentityOp(TFE_Context* ctx, TFE_TensorHandle* a);

// Return a shape op fetching the shape of `a`.
TFE_Op* ShapeOp(TFE_Context* ctx, TFE_TensorHandle* a);

// Return an allreduce op adding up input tensor `in` from `group_size` workers.
TFE_Op* AllReduceOp(TFE_Context* ctx, TFE_TensorHandle* in, int group_size);

// Return a SendOp op `op_name` with send input tensor `in` and attributes

    *   Renames `experimental_hints` in
        `tf.distribute.StrategyExtended.reduce_to`,
        `tf.distribute.StrategyExtended.batch_reduce_to`,
        `tf.distribute.ReplicaContext.all_reduce` to `options`.
    *   Renames `tf.distribute.experimental.CollectiveHints` to
        `tf.distribute.experimental.CommunicationOptions`.
    *   Renames `tf.distribute.experimental.CollectiveCommunication` to