code: def test_len(self):
      assert len(self.dataset) == 704
      assert len(self.dataset_triplet) == 704
  
file_path: mmdetection/tests/test_datasets/test_reid_dataset.py
imports: import os.path
  from unittest import TestCase
  from mmdet.datasets import ReIDDataset
label_desc: Use image node_id 3 for calling the TestReIDDataset obj's underlying member method code with example usage: obj.test_len() without return types