{"ast_node_type":"variable","tokens":[{"end":46,"kind":"keyword","start":0,"text":"let"}]}
        let (mut upper_bounds, _, upper_dup) =
            self.collect_bounding_regions(graph, node_idx, INCOMING, Some(dup_vec));
            self.collect_bounding_regions(graph, node_idx, OUTGOING, Some(dup_vec));