import React from "react";
import { Observable } from "rxjs";
/**
 * A React Component that creates a subscription to the provided observable once
 * the component mounts and it unsubscribes when the component unmounts.
 *
 * @param source$ Source observable that the Component will subscribe to.
 * @param fallback (=null) JSX Element to be rendered before the subscription exists.
 *
 * @remarks This Component doesn't trigger any updates.
 */
export declare const Subscribe: React.FC<{
    source$: Observable<any>;
    fallback?: null | JSX.Element;
}>;