/**
 * Human friendly durations object.
 *
 * @public
 */
export type HumanDuration = {
    years?: number;
    months?: number;
    weeks?: number;
    days?: number;
    hours?: number;
    minutes?: number;
    seconds?: number;
    milliseconds?: number;
};
/**
 * Converts a {@link HumanDuration} to milliseconds.
 *
 * @public
 * @remarks
 *
 * Note that this conversion by definition is an approximation in the absence of
 * an anchor to a point in time and time zone, as the number of milliseconds is
 * not constant for many units. So the conversion assumes 365-day years, 30-day
 * months, and fixed 24-hour days.
 *
 * @param duration - A human friendly duration object.
 * @returns The number of approximate milliseconds that the duration represents.
 */
export declare function durationToMilliseconds(duration: HumanDuration): number;