driverName: "com.example.csi.driver1",
			existingNode: generateNode(
				nodeIDMap{
					"com.example.csi.driver1": "com.example.csi/csi-node1",
				},
				labelMap{
					"com.example.csi/zone": "zoneA",
				},
				nil /*capacity*/),
			existingCSINode: generateCSINode(
				nodeIDMap{
					"com.example.csi.driver1": "com.example.csi/csi-node1",
				},
				nil, /* volumeLimits */

	builder.addLegend()

	if len(g.Nodes) == 0 {
		return
	}

	// Preprocess graph to get id map and find max flat.
	nodeIDMap := make(map[*Node]int)
	hasNodelets := make(map[*Node]bool)

	maxFlat := float64(abs64(g.Nodes[0].FlatValue()))
	for i, n := range g.Nodes {
		nodeIDMap[n] = i + 1
		if float64(abs64(n.FlatValue())) > maxFlat {
			maxFlat = float64(abs64(n.FlatValue()))
		}
	}

	edges := EdgeMap{}