Understanding the Concept of Stream Throttling in TypeScript

declare const response: Http.ClientResponse;

pipe(
  response.stream,
  Stream.broadcast(2, 1),
  Effect.map(Tuple.mapSecond(
    flow(
      Stream.map(u8arr => u8arr.length),
      Stream.scan(0, Number.sum),
      Stream.throttle(Duration.seconds(1)), // emit the latest value every 1 sec, drop other intermediate values
      Stream.tap(x => Ef.log(`Downloaded ${x} bytes`))
    )
  ),
  Ef.map(([responseStream, logStream]) => Stream.merge(responseStream, logStream)),
  Ef.flatMap(Stream.run(fileSystem.sink(outputPath, { flag: 'w' })))
);