human
I wrote the below code

    mocked_app = MockHub.instance(log_level=logging.DEBUG)
    @gen.coroutine
    def make_app():
        (yield mocked_app.initialize([]))
        (yield mocked_app.start())
    io_loop.run_sync(make_app)
    def fin():
        mocked_app.log.handlers = []
        MockHub.clear_instance()
        mocked_app.stop()
    request.addfinalizer(fin)
    return mocked_app

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

@fixture(scope='module')
def app(request, io_loop):