[ CCode ( type_id = "dex_coroutine_get_type ()" ) ]
public sealed class Coroutine : Future
`DexCoroutine` is a [class@Dex.
Future] implemented as a stateful stackless coroutine cooperatively scheduled on a [class@Dex.Scheduler].
Each coroutine stores stackful suspension state and optionally accepts user data via `user_data`.
Use user data passed at spawn time for stateful data.