Pls help to write function

for this:

module Timer: {
  type t
  let setT: (unit => unit, int) => t
  let clearT: t => unit
} = {
  type t = int

  // let setT = ....
  let clearT = (inp: t) => Js.log(j`i got $inp`)

I can’t figure out how to write the setT function.

I’m not sure what to do with unit => unit. This is an example for your reference:

let setT = (cb: unit => unit, inp: t) => {

Open the playground to see it works

Thanks! that’s all I want!