let print_charset (s : set) =
if size s > 126 then
let negset = minus (create_full ()) s in
Printf.printf "neg {";
Hashset.iter (fun c-> Printf.printf "%s," (char_as_string c)) negset;
Printf.printf "}"
else
(Printf.printf "{";
Hashset.iter (fun c-> Printf.printf "%s," (char_as_string c)) s;
Printf.printf "}")