How to get the id from detected object in deepstream?

Hello guys, i want to ask you here, can i get the unique-id from detected object in deepstream ? because when i try the code from deepstream_test_1.py, deepstream_test_3.py, and deepstream_test_4.py. None of them resulting the unique id from detected object.

At first, i was expect that this line of code is for get the unique-id, but in the result when i print this, the result is “-1”
msg_meta.trackingId = long_to_int(obj_meta.object_id)

deepstream_test_1.py, deepstream_test_3.py, and deepstream_test_4.py do not have tracked added, deepstream_test_2.py have tracker, you can use it for getting tracking id.

Thank you amycao