StreamClass.through<S, U>(): StreamClass<Exclude<U, AnyFailure>, Extract<U, AnyFailure>>
StreamClass#through as a static: Stream.through(source, …) is
Stream.from(source).through(…).
await Stream.through([1, 2], async function* (els) { yield* els; }).collect(); // [1, 2]
StreamClass<Exclude<U, AnyFailure>, Extract<U, AnyFailure>>