/**
 * Sleeps the workflow for a specified duration, deterministically.
 * On replay, it will not actually sleep again, but resume after sleep.
 *
 * @param {string} duration - A human-readable duration string (e.g., '1m', '2 hours').
 * @returns {Promise<number>} The resolved duration in seconds.
 */
export declare function sleepFor(duration: string): Promise<number>;