import { IterableX } from '../iterable';
/**
 * Returns elements with a distinct key value by using the specified comparer to compare key values.
 * @param source Source sequence.
 * @param {function(value: TSource): TKey} [keySelector] Key selector.
 * @param {function(x: TKey, y: TKey): boolean} [comparer] Comparer used to compare key values.
 * @return {Iterable<T>} Sequence that contains the elements from the source sequence with distinct key values.
 */
export declare function distinct<TSource, TKey>(source: Iterable<TSource>, keySelector?: (value: TSource) => TKey, comparer?: (x: TKey, y: TKey) => boolean): IterableX<TSource>;