code: def test_del_gt_label(self):
      data_sample = ReIDDataSample()
      self.assertNotIn("gt_label", data_sample)
      data_sample.set_gt_label(1)
      self.assertIn("gt_label", data_sample)
      del data_sample.gt_label
      self.assertNotIn("gt_label", data_sample)
  
file_path: mmdetection/tests/test_structures/test_reid_data_sample.py
imports: from unittest import TestCase
  import numpy
  import torch
  from mmengine.structures import LabelData
  from mmdet.structures import ReIDDataSample
label_desc: Use image node_id 4 for calling the TestReIDDataSample obj's underlying member method code with example usage: obj.test_del_gt_label() without return types