public function __construct($key, ObservableInterface $underlyingObservable, DisposableInterface $mergedDisposable = null)
{
$this->key = $key;
if (null === $mergedDisposable) {
$this->underlyingObservable = $underlyingObservable;
} else {
$this->underlyingObservable = new AnonymousObservable(function ($observer, $scheduler) use($mergedDisposable, $underlyingObservable) {
// todo, typehint $mergedDisposable?
return new CompositeDisposable(array($mergedDisposable->getDisposable(), $underlyingObservable->subscribe($observer, $scheduler)));
});
}
}
