//! [0]
myInstance = QXmlNodeModelIndex();
//! [0]

//! [1]
QFile queryFile(argv[1]);
QFile chemistryData(argv[2]);
QString moleculeName = argv[3];

QXmlQuery query;
query.setQuery(&queryFile, QUrl::fromLocalFile(queryFile.fileName()));

ChemistryNodeModel myNodeModel(query.namePool(), chemistryData);
QXmlNodeModelIndex startNode = myNodeModel.nodeFor(moleculeName);
query.bindVariable("queryRoot", startNode);

QFile out;
out.open(stdout, QIODevice::WriteOnly);

QXmlSerializer serializer(query, &out);
query.evaluateTo(&serializer);
//! [1]