如何重置RxJs流

import { of } from 'rxjs';
import { startWith } from 'rxjs/operators';

const source$ = of(1, 2, 3);
const reset$ = of('reset');
const result$ = reset$.pipe(startWith(source$));

result$.subscribe(console.log); // 输出：1, 2, 3

import { of, concat } from 'rxjs';

const source1$ = of(1, 2, 3);
const source2$ = of(4, 5, 6);
const reset$ = of('reset');
const result$ = concat(reset$, source2$);

result$.subscribe(console.log); // 输出：4, 5, 6

import { of, interval } from 'rxjs';
import { switchMap } from 'rxjs/operators';

const reset$ = of('reset');
const source$ = interval(1000);
const result$ = reset$.pipe(switchMap(() => source$));

result$.subscribe(console.log); // 输出：0, 1, 2, 3, ...