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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def updateDatasetMenu(self):
 """Update the `export` QAction when the Dataset menu is pulled down. This method is a slot. See class ctor for details. """

        enabled = True
        current = self.vtgui.dbs_tree_view.currentIndex()
        if current:
            leaf = self.vtgui.dbs_tree_model.nodeFromIndex(current)
            if leaf.node_kind in (u'group', u'root group'):
                enabled = False

        self.plot_action.setEnabled(enabled)