import { type IAsyncEqualityComparer, type IEqualityComparer, type IGrouping, type IParallelEnumerable, type SelectorKeyType } from "../../types";
type GroupByAsyncFunc = {
    <TSource, TKey extends SelectorKeyType>(source: IParallelEnumerable<TSource>, keySelector: (x: TSource) => Promise<TKey> | TKey): IParallelEnumerable<IGrouping<TKey, TSource>>;
    <TSource, TKey>(source: IParallelEnumerable<TSource>, keySelector: (x: TSource) => Promise<TKey> | TKey, comparer: IEqualityComparer<TKey> | IAsyncEqualityComparer<TKey>): IParallelEnumerable<IGrouping<TKey, TSource>>;
};
export declare const groupByAsync: GroupByAsyncFunc;
export {};