let display (s : Types_unify.term) : string =
let subs = unif true (x 0) s [([], FreeVar 100, [])] in
let size = string_of_int (List.length subs) in
let l_subs = lst_subs_dbg subs size in
let rec aux l =
match l with [] -> ""
|(x::ls) -> if((List.length l)=1)
then (str_term_dbg [] (snd (car x)))
else aux ls
in aux l_subs