// returns list(pair(id, rule))
static L<PairS> mL_rules_addGlobalIDsIfAuthed(S listName) {
  L<S> l = splitAtEmptyLines(mL_raw(listName));
  L<PairS> withIDs = combineWithGlobalIDs(l);
  bool change = false;
  for (PairS p : withIDs)
    if (empty(p.a)) { p.a = aGlobalID(); change = true; }
  if (change && isMechAuthed()) {
    S newText = joinWithEmptyLines(map(withIDs, func(PairS p) -> S {
      prependGlobalIDInNewLineAndIndent(p.a, p.b) }));
    editMechList(listName, newText);
  }
  ret withIDs;
}