code: def test_mot_challenge_dataset_with_visibility(self):
      dataset = MOTChallengeDataset(
          data_prefix=dict(img_path="imgs"),
          ann_file="tests/data/mot_sample.json",
          metainfo=dict(classes=("pedestrian")),
          filter_cfg=dict(filter_empty_gt=True, min_size=32),
          visibility_thr=0.5,
          pipeline=[],
      )
      self.assertEqual(dataset.num_all_imgs, 5)
      self.assertEqual(len(dataset[0]["images"][2]["instances"]), 1)
  
imports: import unittest
  from mmdet.datasets import MOTChallengeDataset
label_desc: Use image node_id 2 for calling the TestMOTChallengeDataset obj's underlying member method code with example usage: obj.test_mot_challenge_dataset_with_visibility() without return types