OCaml Lab 1 Head Scratching

example.ml

type ('key, 'value) avlnode =
    | Leaf
    | Node of int * 
              'key * 
              'value * 
              ('key, 'value) avlnode * 
              ('key, 'value) avlnode

let rec get (node_to_search : ('key, 'value) avlnode) 
            (key_to_search_for : 'key) 
    : 'value option =
        match node_to_search with
        | Leaf -> None
        | Node(_, node_key, node_value, node_left_child, node_right_child) ->
            if node_key = key_to_search_for 
                then Some(node_value)
            else if key_to_search_for < node_key 
                then (get node_left_child key_to_search_for)
            else (get node_right_child key_to_search_for)
            
(* None of this works for me *)
(*
let output = (get a_tree "a")

let print_get_output (output_from_get_function : 'output) =
    match output_from_get_function with
        | Leaf -> Printf.printf "Leaf"
        | _ -> Printf.printf "Default"
;;

(print_get_output output)
*)