loc, func.getFunctionType().getResults());
  graph_op.getBody().push_back(new Block);
  builder.setInsertionPointToEnd(&graph_op.GetBody());
  auto island = builder.create<tf_executor::IslandOp>(
      loc, func.getFunctionType().getResults(),
      tf_executor::ControlType::get(&getContext()), ArrayRef<Value>());
  // Create Fetch.
  ValueRange to_fetch = island.getResults();
  if (to_fetch.size() != 1) {

    // the function body or if they are nested in individual
    // `tf_executor.island`.
    for (Block& block : func.getBody()) BuildClusters(block, builder, info);
    func.walk([&](tf_executor::IslandOp island) {
      BuildClusters(island.GetBody(), builder, info);
    });
  }
}

}  // namespace

std::unique_ptr<OperationPass<ModuleOp>> CreateClusterFormationPass() {