/**
 * Return the latest (maximum) of the given PlainTime values.
 *
 * - Returns null if the array is empty or contains no valid times.
 * - Validation is performed on each item in the array.
 *
 * @param times Array of ISO PlainTime strings (e.g. "14:30:00")
 * @returns The latest time string, or null on invalid input
 *
 * @example maxTime(["14:30:00", "09:00:00", "20:45:00"]) // "20:45:00"
 * @example maxTime([]) // null
 */
export declare function maxTime(times: string[]): string | null;