def rule_function_not_found(self, fun=None):
        """ any function that does not exist will be added as a
        dummy function that will gather inputs for easing into
        the possible future implementation
        """
        sfun = str(fun)
        self.cry('rule_function_not_found:' + sfun)

        def not_found(*a, **k):
            return(sfun + ':rule_function_not_found', k.keys())
        return not_found