code: def test_multi_item_ds(self):
      # one item
      class DS0:
          def __len__(self):
              return 11
  
          def __getitem__(self, i):
              return np.zeros([100, 200, 3])
  
      loader0 = elegy.data.DataLoader(DS0(), batch_size=4)
      batches0 = list(loader0)
      assert len(batches0) == 3
      assert (
          batches0[0].shape == (4, 100, 200, 3)
          and batches0[1].shape == (4, 100, 200, 3)
          and batches0[2].shape == (3, 100, 200, 3)
      )
  
      # three items
      class DS1:
          def __len__(self):
              return 11
  
          def __getitem__(self, i):
              return (
                  np.zeros([100, 200, 3]),
                  np.zeros([100, 200, 3]),
                  np.zeros([100, 200, 3]),
              )
  
      loader1 = elegy.data.DataLoader(DS1(), batch_size=4)
      batches1 = list(loader1)
      assert len(batches1) == 3
      assert isinstance(batches1[0], tuple)
      assert len(batches1[0]) == 3
      assert (
          batches1[0][0].shape == (4, 100, 200, 3)
          and batches1[1][1].shape == (4, 100, 200, 3)
          and batches1[2][2].shape == (3, 100, 200, 3)
      )
  
imports: from unittest import TestCase
  import jax.numpy
  import numpy
  import optax
  import pytest
  import elegy
label_desc: Use image node_id 6 for calling the DataLoaderTestCase obj's underlying member method code with example usage: obj.test_multi_item_ds() and returns: int, np, int, np,  np,  np