static Set<S> combinedMechSetsCI(S... listNames) {
  ret combinedMechSetsCI(asList(listNames));
}

static Set<S> combinedMechSetsCI(Collection<S> listNames) {
  if (empty(listNames)) ret ciSet();
  if (l(listNames) == 1) ret mechSetCI(first(listNames));
  Set<S> set = ciSet();
  for (S listName : listNames)
    set.addAll(mL(listName));
  ret set;
}