@classmethod
def update_json_dict(cls, json_dict):
    """ Update a JSON dictionary before being parsed with class model.
            JSON dictionary is passed by class method from_dict() (see below), and is guaranteed to contain
            at least all expected model keys. Some keys may be associated to None if initial JSON dictionary
            did not provide values for them.

            :param json_dict: a JSON dictionary to be parsed.
            :type json_dict: dict
        """
