import { type ValidDate } from './is-valid-date.js';
type IsBefore = {
    (other: ValidDate): (value: unknown) => value is ValidDate;
    (other: ValidDate, value: unknown): value is ValidDate;
};
/**
 * Asserts that a value is a valid instance of `Date` whose value occurs before that of another.
 *
 * @tags guard, dates, comparator
 */
export declare const isBefore: IsBefore;
export {};