code: def test_warning_raised_on_label():
      class DS(torchdata.Dataset):
          def __init__(self):
              self.x = [1, 2, 3]
              self.label = [1, 1, 1]
  
          def __len__(self):
              return len(self.x)
  
          def __getitem__(self, item):
              return self.x[item], self.label[item]
  
      with warnings.catch_warnings(record=True) as w:
          al = ActiveLearningDataset(DS())
          assert not al.can_label
          assert len(w) == 1
          assert "label" in str(w[-1].message)
  
imports: import pickle
  import unittest
  import unittest.mock
  import warnings
  import datasets
  import numpy
  import pytest
  import torch.utils.data
  from torchvision.transforms import Lambda
  from baal.active import ActiveLearningDataset
label_desc: Use image node_id 3 for calling a global function with example usage: test_warning_raised_on_label() and returns: len, self,  self