RxJs SwitchMap Operator

01.ts

import {of} from "rxjs";
import {delay} from "rxjs/operators";

function simulateHttp(val: any, delay:number) {
    return of(val).pipe(delay(delay));
}

02.ts

console.log('simulating HTTP requests');

const http1$ = simulateHttp("1", 1000);

const http2$ = simulateHttp("2", 1000);

03.ts

http1$.subscribe(
    console.log,
    console.error,
    () => console.log('http1$ completed')
);

http2$.subscribe(
    console.log,
    console.error,
    () => console.log('http2$ completed')
);

04.ts

http1$.subscribe(
    val => console.log(val),
    err => console.error(err),
    () => console.log('http1$ completed')
);

05.ts

const saveUser$ = simulateHttp(" user saved ", 1000);

const httpResult$ = saveUser$.pipe(
    switchMap(sourceValue => {
        console.log(sourceValue);
        return simulateHttp(" data reloaded ", 2000);
        }
     )
);

httpResult$.subscribe(
    console.log,
    console.error,
    () => console.log('completed httpResult$')
);

06.ts

import {interval} from 'rxjs';
import {map} from "rxjs/operators";

function simulateFirebase(val: any, delay: number) {
    return interval(delay).pipe(map(index => val + " " + index));
}

07.ts

const firebase1$ = simulateFirebase("FB-1 ", 5000);
const firebase2$ = simulateFirebase("FB-2 ", 1000);

firebase1$.subscribe(
    console.log,
    console.error,
    () => console.log('firebase1$ completed')
);

firebase2$.subscribe(
    console.log,
    console.error,
    () => console.log('firebase2$ completed')
);

08.ts

const firebase1$ = simulateFirebase("FB-1 ", 5000);
const firebase2$ = simulateFirebase("FB-2 ", 1000);

const firebaseResult$ = firebase1$.pipe(switchMap(sourceValue => {
  console.log("source value " + sourceValue);
  return simulateFirebase("inner observable ", 1000)
}));

firebaseResult$.subscribe(
  console.log,
  console.error,
  () => console.log('completed firebaseResult$')
);

09.ts

const course$ = simulateHttp({id:1, description: 'Angular For Beginners'}, 1000);

const httpResult$ = course$.pipe(switchMap(
  sourceValue => simulateHttp([... returns a lessons array ...], 2000)));

httpResult$.subscribe(
    console.log,
    console.error,
    () => console.log('completed httpResult$')
);

10.ts

const course$ = simulateHttp({id:1, description: 'Angular For Beginners'}, 1000);

const httpResult$ = course$.pipe(
    switchMap(courses => simulateHttp([], 2000)
                  .pipe(
                     map(lessons => [courses,lessons])
                  ),
    )
);

httpResult$.subscribe(
    console.log,
    console.error,
    () => console.log('completed httpResult$')
);

Is the code of 08.ts correct?

Shouldn't

const firebase1$ = simulateFirebase("FB-1 ", 5000);
const firebase2$ = simulateFirebase("FB-2 ", 1000);

const firebaseResult$ = firebase1$.switchMap(sourceValue => {
  console.log("source value " + sourceValue);
  return simulateFirebase("inner observable ", 1000)
});

firebaseResult$.subscribe(
  console.log,
  console.error,
  () => console.log('completed firebaseResult$')
);

look like

const firebase1$ = simulateFirebase("FB-1 ", 5000);
const firebase2$ = simulateFirebase("FB-2 ", 1000);

const firebaseResult$ = firebase1$.switchMap(sourceValue => {
  console.log("source value " + sourceValue);
  return firebase2$;
});

firebaseResult$.subscribe(
  console.log,
  console.error,
  () => console.log('completed firebaseResult$')
);