private void addExactInstances(SNode current, SNode concept, Set<SNode> result, IScope scope) {
   if (current.getConceptFqName().equals(NameUtil.nodeFQName(concept))) {
     result.add(current);
   }
   for (SNode child : current.getChildren()) {
     addExactInstances(child, concept, result, scope);
   }
 }