pub fn center(
  inner: #(Int, Int),
  outer: #(Int, Int),
) -> #(#(Int, Int), #(Int, Int))

pub fn do_fetch(
  request: request.Request(BitArray),
) -> promise.Promise(
  Result(response.Response(BitArray), effect.FetchError),
)

pub fn do_follow(url: uri.Uri) -> promise.Promise(String)

pub fn do_wait(delay: Int) -> promise.Promise(Nil)

pub fn open(
  url: String,
  frame_size: #(Int, Int),
) -> Result(window.Window, String)

pub fn receive_redirect(
  popup: window.Window,
  wait: Int,
) -> promise.Promise(String)

pub fn run(
  task: effect.Effect(a, b),
  unsupported: fn(String) -> a,
) -> promise.Promise(a)

pub fn run_task(
  task: effect.Effect(Result(a, snag.Snag), b),
) -> promise.Promise(Result(a, snag.Snag))