ambExample.swift

import RxSwift

let disposeBag = DisposeBag()

let oldXmenMovies = PublishSubject<String>()
let newXmenMovies = PublishSubject<String>()

oldXmenMovies.amb(newXmenMovies)
  .subscribe(onNext: {
    print($0)
  })
  .disposed(by: disposeBag)

oldXmenMovies.onNext("X-Men")
oldXmenMovies.onNext("X-Men United")
newXmenMovies.onNext("First Class")
oldXmenMovies.onNext("The Last Stand")
newXmenMovies.onNext("Days of Future Past")

// Output:
// X-Men
// X-Men United
// The Last Stand