let searchResults = searchBar.rp.text
  .debounce(interval: 0.3)
  .distinct()
  .flatMap(behavior: .keepLatestTransform) { (query) -> Future<[SearchResult]> in
    return query.isEmpty
      ? .just([])
      : searchGitHub(query: query).recover([])
  }

class MyViewController: UIViewController {
  /* ... */
  @IBOutlet weak var myLabel: UILabel!

  override func viewDidLoad() {
    super.viewDidLoad()
    UIDevice.current.rp.orientation
      .map { $0.description }
      .bind(myLabel.rp.text)
  }
  
  /* ... */
}

class MyViewController: NSViewController {
  let service: MyService

  /* ... */
  
  func fetchAndPresentItems(for request: Request) {
    service.perform(request: request)
      .map(context: self, executor: .primary) { (self, response) in
        return self.items(from: response)
      }
      .onSuccess(context: self) { (self, items) in
        self.present(items: items)
      }
      .onFailure(context: self) { (self, error) in
        self.present(error: error)
      }
  }
  
  func items(from response: Response) throws -> [Items] {
    /* ... extract items from response ... */
  }
  
  func present(items: [Items]) {
    /* ... update UI ... */
  }
}

class MyService {
  func perform(request: Request) -> Future {
    /* ... */
  }
}

extension MyViewController {
  func present(personWithID identifier: String) {
    myService.fetch(personWithID: identifier) {
      (person, error) in

      /* do not forget to dispatch to the main queue */
      DispatchQueue.main.async {

        /* do not forget the [weak self] */
        [weak self] in
        guard let strongSelf = self
          else { return }

        if let person = person {
          strongSelf.present(person: person)
        } else if let error = error {
          strongSelf.present(error: error)
        } else {
          fatalError("There is neither person nor error. What has happened to this world?")
        }
      }
    }
  }
}

extension MyService {
  func fetch(personWithID: String, callback: @escaping (Person?, Error?) -> Void) {
    /* ... */
  }
}

extension MyViewController {
  func present(personWithID identifier: String) {
    myService.fetch(personWithID: identifier)

      /* do not forget to dispatch to the main queue */
      .onComplete(executor: .main) {

        /* do not forget the [weak self] */
        [weak self] (completion) in
        if let strongSelf = self {
          completion.onSuccess(strongSelf.present(person:))
          completion.onFailure(strongSelf.present(error:))
        }
      }
  }
}

extension MyService {
  func fetch(personWithID: String) -> Future {
    /* ... */
  }
}

extension MyViewController {
  func present(personWithID identifier: String) {
    myService.fetch(personWithID: identifier)
      .onSuccess(context: self) { (self, person) in
        self.present(person: person)
      }
      .onFailure(context: self) { (self, error) in
        self.present(error: error)
      }
  }
}

extension MyService {
  func fetch(personWithID: String) -> Future {
    /* ... */
  }
}

func primeNumbers(to n: Int) -> [Int] { /* ... */ }

let futurePrimeNumbers: Future<[Int]> = future { primeNumbers(to: 10_000_000) }

let futureSquaredPrimeNumbers = futurePrimeNumbers
  .map { (primeNumbers) -> [Int] in
    return primeNumbers.map { (number) -> Int
      return number * number
    }
  }

if let fallibleNumbers = futurePrimeNumbers.wait(seconds: 1.0) {
  print("Number of prime numbers is \(fallibleNumbers.success?.count)")
} else {
  print("Did not calculate prime numbers yet")
}

futurePrimeNumbers.onComplete { (falliblePrimeNumbers) in
  print("Number of prime numbers is \(falliblePrimeNumbers.success?.count)")
}

let futureA: Future = /* ... */
let futureB: Future = /* ... */
let futureC: Future = /* ... */
let futureABC: Future<(A, B, C)> = zip(futureA, futureB, futureC)