IOでタイムアウト付き処理をする

I have used the following code elsewhere:

import Lean

open Lean

/--
Return type used internally by `withTimeout`. 
-/
inductive TimeoutResult (α : Type) where
  | success (val : α)
  | timeout

/--
Run a computation with a timeout.
-/
def withTimeout (timeout : UInt32) (x : IO α) : IO α := do
  let timeoutTask ← IO.asTask <| IO.sleep timeout >>= fun _ => return TimeoutResult.timeout
  let mainTask ← IO.asTask (prio := .dedicated) <| TimeoutResult.success <$> x
  match ← IO.waitAny [mainTask, timeoutTask] with
  | .ok <| .success a => 
    IO.cancel timeoutTask
    return a
  | .ok <| .timeout => 
    IO.cancel mainTask
    throw <| .userError s!"Operation timed out after {timeout}ms"
  | .error e => 
    IO.cancel mainTask
    IO.cancel timeoutTask
    throw e

The issue provides a Lean IO timeout snippet but names no repository file, test, or entry point. First inspect the repository's existing IO examples and issue conventions to determine where this example belongs; done should be a clearly placed, working timeout example with the intended behavior documented.