hunk.code_window:  * @deprecated remove in v8. Use {@link concatWith}
    */
   export function concat<T, R>(...observables: Array<ObservableInput<any> | SchedulerLike>): OperatorFunction<T, R> {
     return (source: Observable<T>) => source.lift.call(concatStatic(source, ...(observables as any[])));
   }
hunk.labels: keep keep keep replace keep
hunk.after_edit:   return (source: Observable<T>) => source.lift.call(
       concatStatic(source, ...(observables as any[])),
       undefined
     ) as Observable<R>;
  
hunk.file_path: src/internal/operators/concat.ts
hunk.type: replace
file: import { Operator } from '../Operator';
  import { Subscriber } from '../Subscriber';
  import { Observable } from '../Observable';
  import { OuterSubscriber } from '../OuterSubscriber';
  import { InnerSubscriber } from '../InnerSubscriber';
  import { subscribeToResult } from '../util/subscribeToResult';
  import { MonoTypeOperatorFunction, TeardownLogic, ObservableInput } from '../types';
  import { Subscription } from '../Subscription';
  
  /**
   * Returns an Observable that skips items emitted by the source Observable until a second Observable emits an item.
   *
   * The `skipUntil` operator causes the observable stream to skip the emission of values ​​until the passed in observable emits the first value.
   * This can be particularly useful in combination with user interactions, responses of http requests or waiting for specific times to pass by.
   *
   * ![](skipUntil.png)
   *
   * Internally the `skipUntil` operator subscribes to the passed in observable (in the following called *notifier*) in order to recognize the emission
   * of its first value. When this happens, the operator unsubscribes from the *notifier* and starts emitting the values of the *source*
   * observable. It will never let the *source* observable emit any values if the *notifier* completes or throws an error without emitting
   * a value before.
   *
   * ## Example
   *
   * In the following example, all emitted values ​​of the interval observable are skipped until the user clicks anywhere within the page.
   *
   * ```ts
   * import { interval, fromEvent } from 'rxjs';
   * import { skipUntil } from 'rxjs/operators';
   *
   * const intervalObservable = interval(1000);
   * const click = fromEvent(document, 'click');
   *
   * const emitAfterClick = intervalObservable.pipe(
   *   skipUntil(click)
   * );
   * // clicked at 4.6s. output: 5...6...7...8........ or
   * // clicked at 7.3s. output: 8...9...10..11.......
   * const subscribe = emitAfterClick.subscribe(value => console.log(value));
   * ```
   *
   * @param {Observable} notifier - The second Observable that has to emit an item before the source Observable's elements begin to
   * be mirrored by the resulting Observable.
   * @return {Observable<T>} An Observable that skips items from the source Observable until the second Observable emits
   * an item, then emits the remaining items.
   * @method skipUntil
   * @owner Observable
   */
  export function skipUntil<T>(notifier: Observable<any>): MonoTypeOperatorFunction<T> {
    return (source: Observable<T>) => source.lift(new SkipUntilOperator(notifier));
  }
  
  class SkipUntilOperator<T> implements Operator<T, T> {
    constructor(private notifier: Observable<any>) {
    }
  
    call(destination: Subscriber<T>, source: any): TeardownLogic {
      return source.subscribe(new SkipUntilSubscriber(destination, this.notifier));
    }
  }
  
  /**
   * We need this JSDoc comment for affecting ESDoc.
   * @ignore
   * @extends {Ignored}
   */
  class SkipUntilSubscriber<T, R> extends OuterSubscriber<T, R> {
  
    private hasValue: boolean = false;
    private innerSubscription: Subscription;
  
    constructor(destination: Subscriber<R>, notifier: ObservableInput<any>) {
      super(destination);
      const innerSubscriber = new InnerSubscriber(this, undefined, undefined);
      this.add(innerSubscriber);
      this.innerSubscription = innerSubscriber;
      const innerSubscription = subscribeToResult(this, notifier, undefined, undefined, innerSubscriber);
      // The returned subscription will usually be the subscriber that was
      // passed. However, interop subscribers will be wrapped and for
      // unsubscriptions to chain correctly, the wrapper needs to be added, too.
      if (innerSubscription !== innerSubscriber) {
        this.add(innerSubscription);
        this.innerSubscription = innerSubscription;
      }
    }
  
    protected _next(value: T) {
      if (this.hasValue) {
        super._next(value);
      }
    }
  
    notifyNext(outerValue: T, innerValue: R,
               outerIndex: number, innerIndex: number,
               innerSub: InnerSubscriber<T, R>): void {
      this.hasValue = true;
      if (this.innerSubscription) {
        this.innerSubscription.unsubscribe();
      }
    }
  
    notifyComplete() {
      /* do nothing */
    }
  }
  