import { Observable } from '../observable.js';
export declare function switchMap<T, U>(this: Observable<T>, fn: (val: T) => Observable<U>, max?: number): Observable<U>;
export declare function switchMap<T, U>(this: Observable<T>, fn: (val: T) => Promise<U>, max?: number): Observable<U>;
export declare function switchMap<T, U>(this: Observable<T>, fn: (val: T) => U[], max?: number): Observable<U>;
declare module '../observable.js' {
    interface Observable<T> {
        switchMap: typeof switchMap;
    }
}