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

Reactive Extensions for modern JavaScript

import {Observable} from '../../Observable';
import {observeOn, ObserveOnSignature} from '../../operator/observeOn';

Observable.prototype.observeOn = observeOn;

declare module '../../Observable' {
  interface Observable<T> {
    observeOn: ObserveOnSignature<T>;
  }
}