The output of Term.attrs is not readable

[cxh852456]

Dict.to_sequence (Term.attrs arg) |> Seq.iter ~f:(fun (type_id, v)-> print_endline @@ Value.Typeid.to_string type_id ^ " -> " ^ Value.to_string v);

When i write some like the up , the type_id 's output is not readable and dont know what it is.
how shall i do if i wonder to see what it is.