#include <QtCore/qabstractitemmodel.h>
#ifndef QABSTRACTITEMMODEL_H
class QAbstractItemModel: public QObject{
   /* Some contents are skipped to improve readability */
   public: virtual class QVariant data(class QModelIndex const & index, int role = Qt::DisplayRole) const = 0;
   /* ... */
};
#endif // QABSTRACTITEMMODEL_H