human
Here's a good function header given the following:
I wrote the below code

    assert (num_threads > 0)
    def wrapper(func):
        @functools.wraps(func)
        def inner(*args, **kwargs):
            threads = []
            for i in range((num_threads - 1)):
                thread = threading.Thread(target=func, args=args, kwargs=kwargs)
                threads.append(thread)
            for thread in threads:
                thread.start()
            result = func(*args, **kwargs)
            for thread in threads:
                thread.join()
            return result
        return inner
    return wrapper

What's a good function header?
assistant
#Here's a good function header.

def test_parallel(num_threads=2):