import { Enumerable } from '../enumerable';
import { Lookup } from '../lookup';
declare module '../enumerable' {
    interface Enumerable<TSource> {
        toLookup<TKey, TElement>(keySelector: (item: TSource) => TKey, elementSelector?: (item: TSource) => TElement): Lookup<TKey, TElement>;
    }
}
export declare function toLookup<TSource, TKey, TElement>(this: Enumerable<TSource>, keySelector: (item: TSource) => TKey, elementSelector?: (item: TSource) => TElement): Lookup<TKey, TElement>;