Make sure the Object DOES have an id, already.

def check_is_created(method):
    """ Make sure the Object DOES have an id, already. """
    def check(self, *args, **kwargs):
        if self.id is None:
            raise NotCreatedError('%s does not exists.' %
                                  self.__class__.__name__)
        return method(self, *args, **kwargs)
    return check