// (so it can deactivate itself and activate its GradientTape). Currently
    // that is managed by the language binding and would require relatively
    // messy callbacks.
    call_state_.top().backward_tape->RecordOperation(
        op_type, output_tensors, input_tensor_id, input_dtypes,
        backward_function_getter, backward_function_deleter);
    return absl::OkStatus();