// process #abc local identifier declaration
// => scope + "abc"
svoid tok_hashLocalIdentifiers(L<S> tok, S scope) {
  scope = unnull(scope);
  new HashSet<S> names;

  // first pass (find # declarations)
  for (int k = start; k < j-2; k += 2) {
    S t = get(tok, k+2);
    if (eqGet(tok, k, "#") && isIdentifier(t)) {
      names.add(t);
      replaceTokens(tok, k, k+3, scope + t);
    }
  }
  
  // early exit if nothing to do
  if (empty(names)) ret;
    
  // second pass (references to scoped variables)
  for (int k = 0; k < l(tok); k += 2) {
    S t = get(tok, k);
    if (isIdentifier(t) && names.contains(t))
      tok.set(k, scopeName + "_" + t);
  }
}