code: def test_assign_new_id(self):
      cfg = {
          "_target_": "detectron2.tracking.bbox_iou_tracker.BBoxIOUTracker",
          "video_height": self._img_size[0],
          "video_width": self._img_size[1],
          "max_num_instances": self._max_num_instances,
          "max_lost_frame_count": self._max_lost_frame_count,
          "min_box_rel_dim": self._min_box_rel_dim,
          "min_instance_period": self._min_instance_period,
          "track_iou_threshold": self._track_iou_threshold,
      }
      tracker = instantiate(cfg)
      instances = deepcopy(self._curr_instances)
      instances = tracker._initialize_extra_fields(instances)
      instances = tracker._assign_new_id(instances)
      self.assertTrue(len(instances.ID) == 2)
      self.assertTrue(instances.ID[0] == 2)
      self.assertTrue(instances.ID[1] == 3)
  
file_path: detectron2/tests/tracking/test_bbox_iou_tracker.py
imports: import numpy
  import unittest
  from copy import deepcopy
  from typing import Dict
  import torch
  from detectron2.config import CfgNode
  from detectron2.config import instantiate
  from detectron2.structures import Boxes, Instances
  from detectron2.tracking.base_tracker import build_tracker_head
  from detectron2.tracking.bbox_iou_tracker import BBoxIOUTracker
label_desc: Use image node_id 6 for calling the TestBBoxIOUTracker obj's underlying member method code with example usage: obj.test_assign_new_id() without return types