@classmethod
def get_model(cls):
    """ Return model associated to current class, and cache it for future uses, to avoid
            multiple rendering of model for each class derived from Jsonable. Private method.

            :return: dict: model associated to current class.
        """
    if cls not in cls.__cached__models__:
        cls.__cached__models__[cls] = cls.build_model()
    return cls.__cached__models__[cls]
