/**
 * Returns a new array with all duplicate elements removed, based on the specified key.
 *
 * @example
 * const array = [
 *   { id: 1, name: 'John' },
 *   { id: 2, name: 'Jane' },
 *   { id: 1, name: 'John' },
 * ];
 * const result = uniqueArrayByKey(array, 'id');
 * // [{ id: 1, name: 'John' }, { id: 2, name: 'Jane' }]
 */
export declare function uniqueArrayByKey<T>(array: readonly T[] | null | undefined, key: keyof T): T[];