OCaml Code: Below is the code and attached are images of the error and the expected output the code must print out. Make sure to fix the error and print out the expected output.   interpreter.ml type 'a str = Cons of 'a * ('a stream) | Nil and 'a stream = unit -> 'a str exception Subscript exception Empty let head (s :'a stream) : 'a =   match s () with   | Cons (hd,tl) -> hd   | Nil -> raise Empty    let tail (s :'a stream) : 'a stream =   match s () with   | Cons (hd,tl) -> tl   | Nil -> raise Empty    let null (s : 'a stream) =   match s () with   | Nil -> true   | _ -> false

OCaml Code: Below is the code and attached are images of the error and the expected output the code must print out. Make sure to fix the error and print out the expected output.

interpreter.ml

type 'a str = Cons of 'a * ('a stream) | Nil
and 'a stream = unit -> 'a str

exception Subscript
exception Empty

let head (s :'a stream) : 'a =
  match s () with
  | Cons (hd,tl) -> hd
  | Nil -> raise Empty
  
let tail (s :'a stream) : 'a stream =
  match s () with
  | Cons (hd,tl) -> tl
  | Nil -> raise Empty
  
let null (s : 'a stream) =
  match s () with
  | Nil -> true
  | _ -> false
  
let rec take (n: int) (s: 'a stream) : 'a list =
  match n with
  | n when n > 0 -> head s :: take (n - 1) (tail s)
  | 0 -> []
  | _ -> raise Subscript
  
let rec nth (n: int) (s: 'a stream) : 'a =
  match n with
  | n when n > 0 -> nth (n - 1) (tail s)
  | 0 -> head s
  | _ -> raise Subscript

let rec map (f: 'a -> 'b) (s:'a stream) : 'b stream =
  fun () -> Cons (f (head s), map f (tail s))
  
let rec filter (s: 'a stream) (f: 'a -> bool) : 'a stream =
  if f (head s)
  then fun () -> Cons (head s, filter (tail s) f)
  else filter (tail s) f

let rec sieve (s: int stream) : int stream =
  fun () -> Cons(head s, sieve (filter (tail s) (fun x -> x mod (head s) <> 0)))

let rec fromn (n: int) = fun () -> Cons (n, fromn (n + 1))
let rec fib n m = fun () -> Cons (n, fib m (n+m))

let even : int -> bool = fun x -> x mod 2 = 0
let odd : int -> bool = fun x -> x mod 2 <> 0

let squares : int stream = map (fun x -> x * x) (fromn 1)

let fibs : int stream =
  let rec fib_helper a b =
    fun () -> Cons(a, fib_helper b (a + b))
  in
  fib_helper 0 1

let evenFibs : int stream = filter fibs even
let oddFibs : int stream = filter fibs odd

let is_prime (n: int) : bool =
  let rec is_not_divisible_by (d: int) : bool =
    d * d > n || (n mod d <> 0 && is_not_divisible_by (d + 1))
  in
  n > 1 && is_not_divisible_by 2

let primes : int stream =
  let rec prime_helper n =
    if is_prime n then fun () -> Cons(n, prime_helper (n + 1))
    else prime_helper (n + 1)
  in
  prime_helper 2

let rev_zip_diff : 'a stream -> 'b stream -> ('b * 'a -> 'c) -> ('b * 'a * 'c) stream =
  fun a b f ->
    let rec zip_diff_helper sa sb =
      match (sa (), sb ()) with
      | (Cons (ha, ta), Cons (hb, tb)) ->
          fun () -> Cons ((hb, ha, f (hb, ha)), zip_diff_helper ta tb)
      | _ -> fun () -> Nil
    in
    zip_diff_helper (a ()) (b ())
  
let rec printGenList : 'a list -> ('a -> unit) -> unit =
  fun l f ->
    match l with
    | [] -> ()
    | hd :: tl ->
        f hd;
        printGenList tl f
  
let rec printList : int list -> string -> unit =
  fun l filename ->
    let oc = open_out filename in
    let rec print_element = function
      | [] -> ()
      | [x] -> output_string oc (string_of_int x)
      | x :: xs ->
          output_string oc (string_of_int x ^ " ");
          print_element xs
    in
    print_element l;
    close_out oc
  
let rec printPairList : (int * int) list -> string -> unit =
  fun l filename ->
    let oc = open_out filename in
    let rec print_pair = function
      | [] -> ()
      | [(x, y)] -> output_string oc ("(" ^ string_of_int x ^ ", " ^ string_of_int y ^ ")")
      | (x, y) :: xs ->
          output_string oc ("(" ^ string_of_int x ^ ", " ^ string_of_int y ^ "), ");
          print_pair xs
    in
    print_pair l;
    close_out oc