std::vector<tensorflow::Output> cond_output;
        TF_RETURN_IF_ERROR(CopyGraph(
            &params->cond_graph->graph, &parent->graph, &parent->refiner,
            params->cond_inputs, inputs, scope.impl()->name(),
            scope.impl()->control_deps(), &params->cond_output,
            /* nreturn_nodes */ 1, &cond_output));
        *output = cond_output[0];
        return absl::OkStatus();
      };

// variables.
//
// The returned TF_WhileParams will have all fields initialized except
// `cond_output`, `body_outputs`, and `name`. The `body_outputs` buffer will be
// allocated to size `ninputs`. The caller should build `cond_graph` and
// `body_graph` starting from the inputs, and store the final outputs in
// `cond_output` and `body_outputs`.
//
// If `status` is OK, the caller must call either TF_FinishWhile or