export declare function keyBy<A extends object, K extends keyof {
    [P in keyof A as A[P] extends PropertyKey ? P : never]: unknown;
}>(array: A[], key: K): { [P in A[K] as A[K] extends PropertyKey ? A[K] : never]: A; };
export declare function keyByFunction<A extends object, K extends PropertyKey>(array: A[], keyFn: (x: A) => K): { [P in K]: A; };
export default keyBy;