/**
 * Normalize a bounded, whitespace-canonical five-field cron expression.
 *
 * The caller owns length and control-character checks. Returning `null`
 * indicates unsupported syntax or an out-of-range field.
 */
export declare function normalizeCronExpression(value: string): string | null;
/**
 * Return whether `value` is a portable IANA-style timezone recognized by the
 * current runtime. Raw UTC offsets are intentionally excluded.
 */
export declare function isSupportedIanaTimezone(value: string): boolean;
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