import { AsyncIterableLike } from "../async-like";
import { Retainer } from "./sync";
export interface AsyncRetainer<T> extends AsyncIterable<T> {
    has?(value: T): boolean | Promise<boolean>;
    add(value: T): void | Promise<void>;
}
export interface AsyncRetainerWithHas<T> extends AsyncRetainer<T> {
    has(value: T): boolean | Promise<boolean>;
}
export declare function asyncRetain<T>(iterable: AsyncIterableLike<T>, retainer?: Retainer<T> | AsyncRetainer<T>): AsyncIterable<T>;