TaskClass.completed<T>(value: T): TaskClass<Awaited<T>, never>
Elixir's Task.completed/1: an already-settled task — for handing a precomputed value
to an API that expects a Task, with no recipe left to run.
await Task.completed(42); // 42 await Task.completed(42).yield(0); // 42 — settled before any window
value: T