code: def __getitem__(self, index):
      if index >= self.n_samples:
          raise IndexError()
      np.random.seed(index)
      d1 = np.random.randn(*self.shape).astype("<f4")
      d2 = np.random.randn(*self.shape).astype("<f4")
      d3 = np.random.randn(*self.shape).astype("<f4")
      return index, d1, d2, d3
  
imports: from ctypes import pointer
  from tempfile import NamedTemporaryFile
  from collections import defaultdict
  from assertpy.assertpy import assert_that
  from multiprocessing import cpu_count
  import torch
  from assertpy import assert_that
  import numpy
  from torch.utils.data import Dataset
  from ffcv import DatasetWriter
  from ffcv.fields import IntField, NDArrayField, TorchTensorField
  from ffcv import Loader
label_desc: Use image node_id 3 for calling the TripleDummyActivationsDataset obj's underlying member method code with example usage: obj.__getitem__(index) and returns: index,  d1,  d2,  d3