private List<Var> calcVars() {
List<Var> vars = new ArrayList<>(4);
// Only if not in parent.
// A (var/value) binding may have been copied down to record it's NodeId.
Binding b = idBinding.getParentBinding();
Iterator<Var> iter = idBinding.iterator();
for (Var v : idBinding) {
if (b == null || !b.contains(v)) vars.add(v);
}
return vars;
}
