code: private void loadAllInstances(ZooClassProxy def, boolean subClasses, 
  			MergingIterator<ZooPC> iter, boolean loadFromCache) {
  		for (Node n: nodes) {
  			iter.add(n.loadAllInstances(def, loadFromCache));
  		}
  		
  		if (subClasses) {
  			for (ZooClassProxy sub: def.getSubProxies()) {
  				loadAllInstances(sub, true, iter, loadFromCache);
  			}
  		}
  	}
docs: This method avoids nesting MergingIterators.
  @param def
  @param subClasses
  @param iter