export declare function serverTimezone(): string;
export declare function isValidTimezone(timezone: string): boolean;
export declare function effectiveTimezone(timezone?: string | null): string;
export declare function nextOccurrence(cronExpr: string, after?: Date, timezone?: string | null): Date;
export declare function isValidCron(cronExpr: string): boolean;
export declare function describeCron(cronExpr: string, timezone?: string | null): string;