in the Angular official website instance, about the login section, you don"t quite understand the usage of pipe:
  login(): Observable<boolean> {
    return of(true).pipe(
      delay(1000),
      tap(val => this.isLoggedIn = true)
    );
  }check the pipe usage of nodejs, rxjs, and angular itself, and it doesn"t match. Excuse me, can you help me with the answer?
