human
Solve the following python programming problem given the following code:
@ mock.patch ('ec2api.api.vpn_connection._stop_gateway_vpn_connections', wraps = vpn_connection_api._stop_gateway_vpn_connections) 
@ mock.patch ('ec2api.api.vpn_gateway._delete_subnet_vpnservice', wraps = vpn_gateway_api._delete_subnet_vpnservice) 
def test_detach_vpn_gateway(self, delete_vpnservice, stop_gateway_vpn_connections) : 
    delete_vpnservice_calls = [] 
    delete_vpnservice.side_effect = tools.deepcopy_call_args_saver (delete_vpnservice_calls) 
    mock_manager = mock.Mock () 
    mock_manager.attach_mock (delete_vpnservice, 'delete_vpnservice') 
    mock_manager.attach_mock (<MASK>, 'stop_gateway_vpn_connections') 
    self.set_mock_db_items (fakes.DB_VPN_GATEWAY_1, fakes.DB_VPC_1, fakes.DB_VPN_CONNECTION_1, fakes.DB_SUBNET_1, tools.update_dict (fakes.DB_SUBNET_2, { 
        'vpc_id' : fakes.ID_EC2_VPC_2, 
})) 
    def do_check() : 
        resp = self.execute ('DetachVpnGateway', { 
            'VpcId' : fakes.ID_EC2_VPC_1, 
            'VpnGatewayId' : fakes.ID_EC2_VPN_GATEWAY_1, 
}) 
        self.assertEqual ({ 
            'return' : True, 
}, resp) 
        self.assertEqual (3, self.db_api.update_item.call_count) 
        self.db_api.update_item.assert_has_calls ([mock.call (mock.ANY, self.DB_VPN_GATEWAY_1_DETACHED), mock.call (mock.ANY, tools.update_dict (fakes.DB_VPN_CONNECTION_1, { 
            'os_ipsec_site_connections' : { 
                
}, 
})), mock.call (mock.ANY, self.DB_SUBNET_1_NO_VPN)]) 
        self.neutron.delete_vpnservice.assert_called_once_with (fakes.ID_OS_VPNSERVICE_1) 
        self.assertEqual (1, len (delete_vpnservice_calls)) 
        self.assertEqual (mock.call (mock.ANY, self.neutron, mock.ANY, fakes.DB_SUBNET_1), delete_vpnservice_calls [0]) 
        self.assertIsInstance (delete_vpnservice_calls [0] [1] [2], common.OnCrashCleaner) 
        stop_gateway_vpn_connections.assert_called_once_with (mock.ANY, self.neutron, mock.ANY, self.DB_VPN_GATEWAY_1_DETACHED) 
        self.assertIsInstance (stop_gateway_vpn_connections.call_args [0] [2], common.OnCrashCleaner)...
    
    Given the code above, what is a proper replacement for <MASK>?
assistant
#Here is a proper replacement for <MASK>.
stop_gateway_vpn_connections