/**
 * Subscribe to chunks in the stream, immediately passing any
 * chunks on to the pipe.
 *
 * @group Transformers
 * @example
 * ```
 * --1--2--3--4--5--6--
 *
 * tap(chunk => console.info(x))
 *
 * --1--2--3--4--5--6--
 * ```
 */
export declare function tap<T>(fn: (chunk: T) => unknown): TransformStream<T, T>;