if (nodesToPrune.contains(treeList.getChildLabel(i)))
if (nodesToPrune.contains(treeList.getChildLabel(i))) { collectPreterms(prunedPreterms, treeList.get(i));
  public Sexp prune(Sexp tree) {    if (tree.isSymbol())      return tree;    if (treebank.isPreterminal(tree))      return tree;    if (tree.isList()) {      SexpList treeList = tree.list();      for (int i = 1; i < treeList.length(); i++)	if (nodesToPrune.contains(treeList.getChildLabel(i)))	  treeList.remove(i--);	else	  prune(treeList.get(i));    }    return tree;  }