import { AsyncSequence } from "../../sequency";
export declare class GroupBy {
    /**
     * Groups all elements of the sequence into a map. Keys are determined by the given `keySelector` function.
     *
     * @param {(value: T) => Promise<K> | K} keySelector
     * @returns {Promise<Map<K, T[]>>}
     */
    groupBy<T, K>(this: AsyncSequence<T>, keySelector: (value: T) => Promise<K> | K): Promise<Map<K, T[]>>;
}