import { IfIndexType, Key, Nil, ObjectWith, ValueIteratee } from '../interfaces';
/**
 * Creates an object composed of keys generated from the results of running each element of `collection` thru `iteratee`. The order of grouped values is determined by the order they occur in `collection`. The corresponding value of each key is an array of elements responsible for generating the key.
 *
 * Contribution to minified bundle size, when it is the only function imported:
 * - Lodash: 14,388 bytes
 * - Micro-dash: 322 bytes
 */
export declare function groupBy<T, K extends Key>(collection: T[] | ObjectWith<T> | Nil, iteratee: ValueIteratee<T, K>): {
    [k in K]: IfIndexType<K, T[], T[] | undefined>;
};