def attr_proxy_required(self, obj, attr, required=True):
        key = '%s.%s' % (id(obj), attr)
        self.attr_proxy_map[key] = required
Record that a proxy is/is not required for `obj.attr`.
dataset/ETHPy150Open OpenMDAO/OpenMDAO-Framework/openmdao.main/src/openmdao/main/rbac.py/AccessController.attr_proxy_required