Interface DateUtils

interface DateUtils {
    now: () => Date;
    today: () => Date;
    tomorrow: () => Date;
    yesterday: () => Date;
    addDays: (date: Date, days: number) => Date;
    subtractDays: (date: Date, days: number) => Date;
    addMonths: (date: Date, months: number) => Date;
    subtractMonths: (date: Date, months: number) => Date;
    addYears: (date: Date, years: number) => Date;
    subtractYears: (date: Date, years: number) => Date;
    format: (date: Date, formatStr?: string) => string;
    formatISO: (date: Date) => string;
    formatRelative: (date: Date) => string;
    isToday: (date: Date) => boolean;
    isTomorrow: (date: Date) => boolean;
    isYesterday: (date: Date) => boolean;
    isSameDay: (date1: Date, date2: Date) => boolean;
    startOfDay: (date: Date) => Date;
    endOfDay: (date: Date) => Date;
    startOfMonth: (date: Date) => Date;
    endOfMonth: (date: Date) => Date;
    startOfYear: (date: Date) => Date;
    endOfYear: (date: Date) => Date;
    daysBetween: (date1: Date, date2: Date) => number;
    isValidDate: (date: any) => boolean;
}