/**
 * Groups an array by a specified key.
 * @param array - The array to group.
 * @param key - The key to group the array by.
 * @returns An object where each key is a unique value from the array, and each value is an array of items from the original array that match the key.
 */
export default function groupBy<T>(array: T[], key: keyof T): Record<string, T[]>;