import { Day } from './day.enum';
/**
 *  A function which returns the first date of the current week.
 *
 * @param date - The initial date.
 * @param weekStartDay [default: Day.Sunday] - The first day of the week.
 * @returns - The first date of the current week.
 *
 * @example
 * ```ts-no-run
 * firstDayInWeek(new Date(2016, 0, 15)); // 2016-01-10
 * firstDayInWeek(new Date(2016, 0, 15), Day.Monday); // 2016-01-11
 * ```
 */
export declare const firstDayInWeek: (date: Date, weekStartDay?: Day) => Date;