@reactivex/rxjs/src/add/operator/switchMap.ts

Reactive Extensions for modern JavaScript

import {Observable} from '../../Observable';
import {switchMap, SwitchMapSignature} from '../../operator/switchMap';

Observable.prototype.switchMap = switchMap;

declare module '../../Observable' {
  interface Observable<T> {
    switchMap: SwitchMapSignature<T>;
  }
}