Is it possible to sort numbers in a QTreeWidget column?

class TreeWidgetItem : public QTreeWidgetItem {
  public:
  TreeWidgetItem(QTreeWidget* parent):QTreeWidgetItem(parent){}
  private:
  bool operator<(const QTreeWidgetItem &other)const {
     int column = treeWidget()->sortColumn();
     return text(column).toLower() < other.text(column).toLower();
  }
};

class TreeWidgetItem(QtGui.QTreeWidgetItem):

    def __init__(self, parent=None):
        QtGui.QTreeWidgetItem.__init__(self, parent)

    def __lt__(self, otherItem):
        column = self.treeWidget().sortColumn()
        return self.text(column).toLower() < otherItem.text(column).toLower()

"19"[0] != "121"[0] ? // no
"19"[1] != "121"[1] ? // yes
     '9' > '2' ?      // yes
          return some value that indicates "19" greater than "121";