static TreeSet<S> litciset(S... items) {
  TreeSet<S> set = caseInsensitiveSet();
  for (S a : items) set.add(a);
  ret set;
}

ifclass Symbol
static TreeSet<Symbol> litciset(Symbol... items) {
  TreeSet<Symbol> set = treeSet(); // HashSet would also do, but we might have the return type fixed somewhere, and they might want a NavigableMap.
  for (Symbol a : items) set.add(a);
  ret set;
}
endif