// Collect the control operands separately, they will be held by the island.
  mlir::SmallVector<mlir::Value, 8> control_operands;

  for (const auto* input_edge : in_edges) {
    const Node& input_node = *input_edge->src();
    if (input_node.IsSource()) {
      if (in_edges.size() != 1) {
        return errors::FailedPrecondition(
            "The node has other inputs besides the _Source node");