let get_depth (tree : 'a tree) (n : 'a tree) : int =
let rec aux depth { content = t ; children = l } =
if t = get_content n then depth else auxaux (succ depth) l
and auxaux depth = function
| [] -> raise Not_found
| hd::tl -> try aux depth hd with Not_found -> auxaux (succ depth) tl
in aux 0 tree