def GetSelectedContextsAndNodes(self):
        """
        returns a list of (ctx, node)
        for use from PyCrust as 'get_selected()'
        """
        items = self._dag_tree.GetSelections()
        ctxs_and_nodes = []
        for item in items:
            data = self._dag_tree.GetPyData(item)
            if not data:
                return
            ctx, node = data
            if (ctx, node) is not ctxs_and_nodes:
                ctxs_and_nodes.append((ctx, node))
        return ctxs_and_nodes
dataset/ETHPy150Open manahl/mdf/mdf/viewer/frame.py/MDFViewerFrame.GetSelectedContextsAndNodes/operator `not in` -> `is not`