let iosh_defId_find iosh defId =
(* int -> IOS.t -> int option -> int option*)
let get_vid vid ios io =
match io with
Some(i) -> Some(i)
| None ->
let there = IOS.exists
(function None -> false
| Some(i') -> defId = i') ios in
if there then Some(vid) else None
in
IH.fold get_vid iosh None