/**
 * Return the UTC datetime string with a trailing Z removed if present.
 *
 * - Uses regex to remove trailing "z" or "Z".
 * - Returns "" for invalid input.
 *
 * @param value UTC datetime string (ISO 8601)
 * @returns UTC datetime string without trailing Z or "" on invalid input
 *
 * @example chopUtc("2024-03-10T12:00:00Z") // "2024-03-10T12:00:00"
 * @example chopUtc("2024-03-10T12:00:00") // "2024-03-10T12:00:00"
 * @example chopUtc("invalid") // ""
 */
export declare function chopUtc(value: string): string;