export declare function isDate(value: any): boolean;
export declare function toDate(value: any): Date;
export declare function isValidDate(value: any): boolean;
export declare function startOfWeek(value: Date, firstDayOfWeek?: number): Date;
export declare function startOfWeekYear(value: Date, { firstDayOfWeek, firstWeekContainsDate }?: {
    firstDayOfWeek?: number | undefined;
    firstWeekContainsDate?: number | undefined;
}): Date;
export declare function getWeek(value: Date, { firstDayOfWeek, firstWeekContainsDate }?: {
    firstDayOfWeek?: number | undefined;
    firstWeekContainsDate?: number | undefined;
}): number;