```python from concurrent.futures import ThreadPoolExecutor, as_completed

def main(): with ThreadPoolExecutor(max_workers=len(URLs)) as executor: tasks = {} for url in URLs: future = executor.submit(fetch_url, url) tasks[future] = url

    for future in as_completed(tasks):
        title = future.result()
        url = tasks[future]
        print(f"URL: {url}\nTitle: {title}")

```

```python from concurrent.futures import ThreadPoolExecutor, as_completed

with ThreadPoolExecutor(max_workers=5) as executor: executor.submit(do_something_blockint) ```