code: def test_npz3(self):
      test_data1 = np.random.randint(0, 256, size=[3, 4, 4])
      test_data2 = np.random.randint(0, 256, size=[3, 4, 4])
      with tempfile.TemporaryDirectory() as tempdir:
          filepath = os.path.join(tempdir, "test_data.npz")
          np.savez(filepath, test1=test_data1, test2=test_data2)
  
          reader = NumpyReader(npz_keys=["test1", "test2"])
          result = reader.get_data(reader.read(filepath))
      np.testing.assert_allclose(
          result[1]["spatial_shape"], test_data1.shape
      )
      np.testing.assert_allclose(result[0].shape, (2, 3, 4, 4))
      np.testing.assert_allclose(
          result[0], np.stack([test_data1, test_data2])
      )
  
file_path: MONAI/tests/test_numpy_reader.py
imports: from __future__ import annotations
  import os
  import sys
  import tempfile
  import unittest
  import numpy
  from monai.data import DataLoader, Dataset, NumpyReader
  from monai.transforms import LoadImage, LoadImaged
  from tests.utils import assert_allclose
label_desc: Use image node_id 4 for calling the TestNumpyReader obj's underlying member method code with example usage: obj.test_npz3() without return types