def by_schema(cls, **kwa):
    """
    Will return only those claims that are listed in the Class definition.

    :param cls: A subclass of :py:class:´oidcmsg.message.Message`
    :param kwa: Keyword arguments
    :return: A dictionary with claims (keys) that meets the filter criteria
    """
    return dict([(key, val) for key, val in kwa.items() if key in cls.c_param])