public ExtendedIterator<Domain> executeBindings(
     List<Stage> outStages, NamedGraphMap args, Node[] nodes) {
   Mapping map = new Mapping(nodes);
   ArrayList<Stage> stages = new ArrayList<Stage>();
   addStages(stages, args, map);
   if (constraint.isComplex()) stages.add(new ConstraintStage(map, constraint));
   outStages.addAll(stages);
   variableCount = map.size();
   return filter(connectStages(stages, variableCount));
 }
 public int size() {
   return parent.size();
 }