export interface FlattenOptions { delimiter?: string; maxDepth?: number; safe?: boolean; transformKey?: (key: string) => string; } export function flatten(target: T, options?: FlattenOptions): R; export interface UnflattenOptions { delimiter?: string; object?: boolean; overwrite?: boolean; transformKey?: (key: string) => string; } export function unflatten(target: T, options?: UnflattenOptions): R;