discontinued slightly odd write_prv, which would still write .prv files the first time, and deprive add-on tools from date stamp change (cf. 157e74588c49);
structure ROOT =
struct
structure Codegen =
struct
fun lookup ((k, v) :: xs) l =
(if ((k : string) = l) then SOME v else lookup xs l)
| lookup [] l = NONE;
end; (*struct Codegen*)
end; (*struct ROOT*)