type InResult<O, K extends PropertyKey> = [
    O extends infer E ? K extends keyof E ? E & Record<K, Required<E>[K]> : never : never
] extends [infer R] ? [R] extends [never] ? Record<K, unknown> : R extends O ? R : never : never;
export declare const in_: <K extends PropertyKey>(key: K) => <O extends object>(object: O) => object is InResult<O, K>;
export {};