@Nullable
protected Double[] get(final Event e) {
final Location l1 = loc1.getSingle(e), l2 = loc2.getSingle(e);
if (l1 == null || l2 == null || l1.getWorld() != l2.getWorld())
return new Double[0];
return new Double[] {l1.distance(l2)};
}
@Override
public String toString(final @Nullable Event e, final boolean debug) {
return "distance between " + loc1.toString(e, debug) + " and " + loc2.toString(e, debug);