type storage = int

(* variant defining pseudo multi-entrypoint actions *)

type action =
  Increment of int
| Decrement of int

let add (a: int) (b: int) : int = a + b
let sub (a: int) (b: int) : int = a - b

(* real entrypoint that re-routes the flow based on the action provided *)

let main (p: action) storage =
  let storage =
    match p  with
      Increment n -> add storage n
    | Decrement n -> sub storage n
  in ([] : operation list), storage