{"ast_node_type":"other","tokens":[{"end":49,"kind":"keyword","start":0,"text":"parent.push(frame.pre_order_idx);"}]}
                parent.push(frame.pre_order_idx);
                real_to_pre_order[successor] = Some(pre_order_idx);
                stack.push(PreOrderFrame { pre_order_idx, iter: graph.successors(successor) });