/**
 * Checks whether the input value is a native Promise by testing for a `.then` method.
 *
 * @param obj - The value to test.
 * @returns `true` if the value is a Promise, `false` otherwise.
 */
export declare function isPromise<T, S>(obj: Promise<T> | S): obj is Promise<T>;
/**
 * Checks whether the input value is PromiseLike (i.e., has a `.then` method), which
 * includes both native Promises and custom thenables.
 *
 * @param obj - The value to test.
 * @returns `true` if the value is PromiseLike, `false` otherwise.
 */
export declare function isPromiseLike<T, S>(obj: PromiseLike<T> | S): obj is PromiseLike<T>;