export declare const isDuration: (str: string) => boolean;
export declare class Duration {
    years: number;
    months: number;
    weeks: number;
    days: number;
    hours: number;
    minutes: number;
    seconds: number;
    constructor(years?: number, months?: number, weeks?: number, days?: number, hours?: number, minutes?: number, seconds?: number);
    abs(): Duration;
    static from(durationLike: unknown): Duration;
}
export declare function applyDuration(date: Date, duration: Duration): Date | null;
export declare function withinDuration(a: Date, b: Date, str: string): boolean;