/**
 * Get keys from an object
 * @example
 * ```ts
 * const myObj = { a: 1, b: 2, c: 3 };
 * console.log(keys(myObj));
 * // Output: ['a', 'b', 'c']
 * ```
 * @param obj object with string keys
 * @returns the keys of the object passed as parameter
 */
export declare function keys<T>(obj?: T): string[];