(* Baseline: fizzbuzz returning a list of strings *)
let fizzbuzz n =
  let acc = ref [] in
  for i = 1 to n do
    let s =
      if i mod 15 = 0 then "FizzBuzz"
      else if i mod 3 = 0 then "Fizz"
      else if i mod 5 = 0 then "Buzz"
      else Int.to_string i
    in
    acc := s :: !acc
  done ;
  List.rev !acc
;;

(* Concatenated for a deterministic check value via String.length *)
String.length (String.concat "," (fizzbuzz 15))