/**
 * Flattens an object to a single level, with the nested keys separated by a `delimiter`.
 * @example
 * ```ts
 * deepFlatten({ a: { b: 1, c: 2 } });
 * // => { 'a.b': 1, 'a.c': 2 }
 *
 * deepFlatten({ a: { b: 1, c: 2 } }, '/');
 * // => { 'a/b': 1, 'a/c': 2 }
 *
 * deepFlatten({ a: { b: 1, c: { d: 'some val' } }, d: 3 });
 * // => { 'a.b': 1, 'a.c.d': 'some val', d: 3 }
 *
 * ```
 * @param {string} [delimiter]
 */
export declare function deepFlatten(obj: Record<string, any>, delimiter?: string): Record<string, any>;