import { HashableEqualityComparer } from "../../collections/equalityComparison";
import { LinqWrapper } from "../linqWrapper";
import { SequenceElementSelector } from "./typing";
import { PipeBody } from "../../pipables";
/**
 * Represents basic traits of a group after grouping the input sequence.
 *
 * @template TKey type of the group key.
 * @template TValue type of the element from the input sequence.
*/
export interface LinqGrouping<TKey, TValue> {
    /** The grouping key. */
    key: TKey;
    /** The abstracted representation of value sequence. */
    values: LinqWrapper<TValue>;
}
export declare function groupBy<T, TKey>(keySelector: SequenceElementSelector<T, TKey>, comparer?: HashableEqualityComparer<TKey>): PipeBody<LinqWrapper<T>, LinqWrapper<LinqGrouping<TKey, T>>>;
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