/**
 * Check if a value is a Date instance
 * @param {*} value The value to check.
 * @returns {value is Date} True if value is a Date, false otherwise.
 */
export declare function isDate(value: any): value is Date;
/**
 * Check if a value is iterable.
 * @param {*} value The value to check.
 * @returns {value is Iterable} True if value is iterable, false otherwise.
 */
export declare function isIterable(value: any): value is Iterable<any>;
/**
 * Return the input value if it passes a test.
 * Otherwise throw an error using the given message generator.
 * @template T
 * @param {T} value The value to check.
 * @param {(value: T) => boolean} test The test function.
 * @param {(value: *) => string} message Message generator.
 * @returns {T} The input value.
 * @throws if the value does not pass the test
 */
export declare function check<T>(value: T, test: (value: T) => boolean, message: (value: any) => string): T;
/**
 * Return the input value if it exists in the provided set.
 * Otherwise throw an error using the given message generator.
 * @template T
 * @param {T} value The value to check.
 * @param {T[] | Record<string,T>} set The set of valid values.
 * @param {(value: *) => string} [message] Message generator.
 * @returns {T} The input value.
 * @throws if the value is not included in the set
 */
export declare function checkOneOf<T>(value: T, set: T[] | Record<string, T>, message?: (value: any) => string): T;
/**
 * Return the first object key that pairs with the given value.
 * @param {Record<string,any>} object The object to search.
 * @param {any} value The value to lookup.
 * @returns {string} The first matching key, or '<Unknown>' if not found.
 */
export declare function keyFor(object: Record<string, any>, value: any): string;