human
I wrote the below code

    fetcher = FetchStrategyComposite()
    fetcher.append(URLFetchStrategy(mock_archive.url))
    @property
    def fake_fn(self):
        return fetcher
    orig_fn = PackageBase.fetcher
    PackageBase.fetcher = fake_fn
    (yield)
    PackageBase.fetcher = orig_fn

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

@pytest.fixture()
def mock_fetch(mock_archive):