export declare class DateHelper {
    static addSeconds(date: Date, seconds: number): Date;
    static addMinutes(date: Date, minutes: number): Date;
    static addHours(date: Date, hours: number): Date;
    static addDays(date: Date, days: number): Date;
    static addMonths(date: Date, months: number): Date;
    static addYears(date: Date, years: number): Date;
}