def METHOD_NAME(syn, project, schedule_for_cleanup):
    """Fetches one item from the Project and updates it with a new file."""
    while syn.test_keepRunning:
        id = get_all_ids_from_Project(syn, project)
        if len(id) <= 0:
            continue
        id = id[random.randrange(len(id))]
        entity = syn.get(id)
        # Replace the file and re-store
        path = utils.make_bogus_data_file()
        schedule_for_cleanup(path)
        entity.path = path
        entity = store_catch_412_HTTPError(syn, entity)
        if entity is not None:
            assert os.stat(entity.path) == os.stat(path)
        sleep_for_a_bit()