import { Enumerable } from './enumerable';
import { Grouping } from './grouping';
export declare class Lookup<TKey, TElement> extends Enumerable<Grouping<TKey, TElement>> {
    get(key: TKey): Enumerable<TElement>;
    get size(): number;
    contains(key: TKey): boolean;
    [Symbol.iterator](): IterableIterator<Grouping<TKey, TElement>>;
    toString(): string;
}