def _on_tree_item_collapsed(self, event):

        # Which item was collapsed?
        wxid = event.GetItem()

        # The item data is a tuple.  The first element indicates whether or not
        # we have already populated the item with its children.  The second
        # element is the actual item data.
        populated, element = self.control.GetPyData(wxid)

        # Make sure that the element's 'closed' icon is displayed etc.
        self._refresh_element(wxid, element)

        # Trait notification.
        self.element_collapsed = element

        return
Test that update changes the right number of rows for an empty queryset
dataset/ETHPy150Open enthought/pyface/pyface/viewer/tree_viewer.py/TreeViewer._on_tree_item_collapsed--crossover with--dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.4/tests/modeltests/update/tests.py/SimpleTest.test_empty_update