// We pre-allocate the array of operands and populate it using the
// `output name to position` and `control output to position` populated
// previously.
SmallVector<Value> ret vals(func.ret size() + func.control ret size(),
              Value());
for (const auto& ret val : func.ret()) {
 auto position = output name to position.find(ret val.first);
 if (position == output name to position.end())
  return InvalidArgument(
    "Can't import function, returned value references unknown output "
    "argument ",
    ret val.first);
 ret vals[position->second] =
   value manager.GetValueOrCreatePlaceholder(ret val.second);
}
for (const auto& ret val : func.control ret()) {
 auto position = control output to position.find(ret val.first);
 if (position == control output to position.end())
  return InvalidArgument(
    "Can't import function, returned value references unknown output "
    "argument ",
    ret val.first);
 Value result = value manager.GetValueOrCreatePlaceholder(
   (Twine("^") + ret val.second).str());

// Process every node and create a matching MLIR operation
for (const NodeDef& node : nodes) {
 if (node.op().empty()) return InvalidArgument("empty op type");
 OperationState state(unknown loc, absl::StrCat("tfg.", node.op()));
 // Fetch the inputs, creating placeholder if an input hasn't been visited.
 for (const std::string& input : node.input())
  state.operands.push back(
    value manager.GetValueOrCreatePlaceholder(input));