import { Observable, Subscribable } from 'rxjs';
/**
 * Observable operator which calls the provided callbacks when observable
 * is subscribed to or unsubscribed from
 *
 * @param onSubscribe - function which is called when observable
 *  is subscribed to
 * @param onUnsubscribe - function which is called when observable
 *  is unsubscribed from
 */
export declare function onSubscription<T>(onSubscribe: (() => void) | undefined, onUnsubscribe: (() => void) | undefined): (source: Subscribable<T>) => Observable<T>;