more explicit indication of Output.Private_Hooks (still public to accomodate clones of Proof General for now);
(* Classical Higher-order Logic -- batteries included *)
use_thys ["Library", "List_Prefix", "List_lexord", "Sublist_Order",
"Code_Char_chr", "Code_Integer", "Efficient_Nat", "Executable_Set"(*, "Code_Prolog"*)];