/**
 * A class for formatting a numeric value in the unit of milliseconds into a display value representing its
 *  days, hours, minutes, and seconds.
 */
export declare class DurationFormatter {
    private readonly lang;
    private readonly daysFormatter;
    private readonly hoursFormatter;
    private readonly minutesFormatter;
    private readonly secondsFormatter;
    private readonly scientificSecondsFormatter;
    constructor(lang: string);
    format(milliseconds: number | null | undefined): string;
}