let cut_string_to_length deb s n =
let ldb = String.length deb in
let len = String.length s in
if ((len+ldb)<n) then
let tab = String.make (n - len - ldb) ' ' in
(Printf.sprintf "%s%s" deb s)^tab
else
String.sub (Printf.sprintf "%s%s" deb s) 0 n