static <A> A safeUnstructureAllowingCertainClasses(S s, S... allowedClasses) {
  new Set<S> allowedClassesSet;
  fOr (S c : allowedClasses) {
    set.add("main$" + name);
    set.add("loadableUtils.utils$" + name);
  }
  O classFinder = func(S name) {
    if (!allowedClassesSet.contains(name)) fail("Class not allowed to unstructure: " + name);
    ret classForName(name);
  };
  ret (A) unstructure(s, false, classFinder);
}