import { ConnectableObservable, interval, Observable, Subject } from 'rxjs';import { multicast } from 'rxjs/operators';const observable = interval(1000);/** * 1. Define a new Subject. */const subject = new Subject<number>();/** * 2. Use the multicast operator in the pipe of the source observable. */const multicasted = observable.pipe(multicast(subject)) as ConnectableObservable<number>;;/** * 3. Subscribe to the multicasted observable and log out the next notification values. */const sub = multicasted.subscribe(console.log);/** * 4. Connect the subject to the source observable. */multicasted.connect();