/**
 * Coerces Errors to `never`.
 */
export type FinalValue<V> = V extends Error ? never : V;
/**
 * Returns a Promise that settles after the provided `delay`, which may be
 * expressed as a number (of milliseconds) or as a string ('10 seconds').
 *
 * If an instance of `Error` was passed as the second argument, the Promise will
 * reject with the error. If any other value was provided, the Promise will
 * resolve with the value.
 */
declare function sleep<V = any>(delay: string | number, value?: V): Promise<FinalValue<V>>;
declare namespace sleep {
    var sync: <T = any>(delay: string | number, value?: T | undefined) => FinalValue<T>;
}
export default sleep;
/**
 * @deprecated Pass an Error to `sleep` to cause a rejection.
 *
 * Returns a Promise that rejects after the provided delay. Delay may be
 * expressed as a number (of milliseconds) or as a string.
 */
export declare function rejectAfter<T = any>(delay: string | number, value?: T): Promise<void>;