/**
 * Validates a cron expression.
 * Returns null if valid, or an error message if invalid.
 */
export declare function validateCron(expression: string): string | null;
/**
 * Returns the next run time for a cron expression as a Date, or null if none.
 */
export declare function getNextRunTime(expression: string): Date | null;
/**
 * Formats a cron expression into a human-readable description.
 */
export declare function formatCronHuman(expression: string): string;
//# sourceMappingURL=cron.d.ts.map