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