method pp_term_operator fmt op es =
match op , es with
| Infix s , [a;b] -> Format.fprintf fmt "%a@ %s@ %a"
self#pp_term_atom a s self#pp_term_atom b
| Prefix s , [a] -> Format.fprintf fmt "%s%a" s self#pp_term_atom a
| Postfix s , [a] -> Format.fprintf fmt "%a%s" self#pp_term_atom a s
| (Infix s | Postfix s | Prefix s) , _ ->
Wp_parameters.fatal "Logic:operator(%s) with %d arguments" s
(List.length es)
| Assoc(nil,op) , _ -> pp_assoc nil op self#pp_term_atom fmt es
| Call id , _ -> self#pp_term_call fmt id es
| Extern f , _ -> self#pp_term_extern fmt f es