def parent(self, index=None):
'''Returns the parent of the model item with the given index.
If the item has no parent, an invalid QModelIndex is returned.'''
if index is None: # Overload with QObject.parent()
return QObject.parent(self)
if not index.isValid():
return QModelIndex()
nodePref = self.index2Pref(index)
parentPref = nodePref.qt_get_parent()
if parentPref == self.rootPref:
return QModelIndex()
return self.createIndex(parentPref.qt_parents_index_of_me(), 0, parentPref)
