class_docstr: Dataset returns even number for labeled samples and odd numbers for unlabeled samples.
      
class_docstr_tok: ["Dataset","returns","even","number","for","labeled","samples","and","odd","numbers","for","unlabeled","samples","."]
code: def __len__(self):
      return len(self.data)
  
file_path: baal/tests/utils/ssl_iterator_test.py
imports: import unittest
  import pytest
  import torch
  from torch.utils.data import Dataset, ConcatDataset
  from baal.active import ActiveLearningDataset
  from baal.utils.ssl_iterator import SemiSupervisedIterator
label_desc: Use image node_id 3 for calling the SSLTestDataset obj's underlying member method code with example usage: obj.__len__() and returns: len