order = {
let graph = reorder.graph().nodes(nodes).links(links).init();
const barycenter = reorder.barycenter_order(graph),
improved = reorder.adjacent_exchange(
graph,
barycenter[0],
barycenter[1]
)[0];
const b = new Map(improved.map((lo, i) => [i, lo]));
return d3.range(improved.length).map((i) => b.get(i));
}