final Set<String> nameUsed = new HashSet<String>();
final Map<JsName, Integer> nameToFragment = new HashMap<JsName, Integer>();
for (int i = 0; i < jsProgram.getFragmentCount(); i++) {
final Integer fragId = i;
new JsVisitor() {
@Override
public void endVisit(JsForIn x, JsContext ctx) {
if (x.getIterVarName() != null) {
nameUsed.add(x.getIterVarName().getIdent());
}