export declare class Subject<T> {
    #private;
    constructor();
    next(value: T): void;
    subscribe(callback: (value: T) => any | Promise<any>): () => boolean;
}
declare const UNSET: unique symbol;
export declare class ReplaySubject<T> {
    #private;
    get value(): typeof UNSET | T;
    constructor(initialValue?: T);
    get(): typeof UNSET | T;
    next(value: T): void;
    subscribe(callback: (value: T) => any | Promise<any>): () => boolean;
    tx(callback: (value: T) => T): void;
    tx(callback: (value: T) => Promise<T>): Promise<void>;
}
export {};