OCJvanDijk

class ProgressFuture<Output, Failure: Error> {
    let future: Future<Output, Failure>
    let progress: Progress

    init(_ attemptToFulfill: @escaping (@escaping Future<Output, Failure>.Promise, Progress) -> Void) {
        let progress = Progress()
        self.future = Future { promise in attemptToFulfill(promise, progress) }
        self.progress = progress
    }
}