import { ObjBase, ObjBaseBy, Prop } from '../typings/types';
interface KeyBy {
    <O, KT extends string>(fn: ObjBaseBy<O, KT>, obj: O): Record<KT, O[keyof O]>;
    <K extends Prop, V, KT extends string>(fn: ObjBase<K, V, KT>): <O extends Record<K, V>>(obj: O) => Record<KT, O[keyof O]>;
}
/**
 * Creates an object composed of keys generated from the results of running
 * each element of object thru `fn`. The corresponding value of
 * each key is the last element responsible for generating the key
 *
 * @param {Function} fn The function to transform value to group key. Receives three argument, `value`, `key`, `obj`.
 * @param {Object} obj The obj to iterate over.
 * @returns {Object} Returns the composed aggregate object.
 * @example
 *
 * keyBy(x => x < 2, { a: 0, b: 1, c: 3});// => { false: 1, true: 3 }
 */
declare const _default: KeyBy;
export default _default;