@classmethod
def to_json(cls):
    """
        to_json is an hybridmethod, the goal is to provide two different
        implementations when it is used as a class (DataSource) or as
        an instance (Widget).
        """
    return {'data_url': cls.data_url, 'name': cls.__name__, 'type':
        'content', 'content': cls.__name__, 'title': cls.title}
