import { NostrEvent } from "./event.js";
export declare const ExpirationTimestampSymbol: unique symbol;
/** Returns the NIP-40 expiration timestamp for an event */
export declare function getExpirationTimestamp(event: NostrEvent): number | undefined;
/** Checks if an event has expired based on the NIP-40 expiration timestamp */
export declare function isExpired(event: NostrEvent): boolean;