}
public static Collection trimForest(Collection computationForest,
Collection nonEnumerizableList) {
final Collection ret = new LinkedHashSet(computationForest);
final TreeTrimingVisitor visitor = new TreeTrimingVisitor(ret,
nonEnumerizableList);
// for each root in the computation forest
for (final Iterator it = computationForest.iterator(); it.hasNext();) {
final ComputationNode root = (ComputationNode) it.next();