Pysistence example

    base_data_sources = make_dict({
        'business': BusinessDataSource(clientUS),
        'money': USMoneyDataSource(clientUS),
        'technology': TechnologyDataSource(clientUS),
        'sport': SportUSDataSource(clientUS),
        'comment': CommentIsFreeDataSource(clientUS),
        'culture': CultureDataSource(clientUS),
        'top_stories': TopStoriesDataSource(clientUS),
        'video': VideoDataSource(clientUS),
    })

    data_sources = {
        'v1' : base_data_sources,
        'v3' : base_data_sources,
        'v6' : base_data_sources.using(
            most_shared_us = MostSharedDataSource(clientUS)
        ),
    }