Standard      map[string]bool   // map package path to whether it's in the standard library
	PackageVetx   map[string]string // map package path to vetx data from earlier vet run
	VetxOnly      bool              // only compute vetx data; don't report detected problems
	VetxOutput    string            // write vetx data to this output file
	GoVersion     string            // Go version for package

    for (int what : {from, to}) {
      if (operation_index_to_operator_index.count(what) == 0) {
        module_.emitError(
            "dangling control edge -- at least one vertex Operation isn't a "
            "flatbuffer Operator.");
      }
    }
    model_control_dependencies_[index].emplace_back(
        operation_index_to_operator_index[from],