public void dump(Appendable out, int d, String indent) {
Formatter f = new Formatter(out);
f.format("%s%d: %s%n", indent, d, value);
int l = links.size();
for (int i = 0; i < l; i++) {
BKNode<V> node = links.get(i);
if (node == null) continue;
node.dump(out, i, " " + indent);
}
}