code: def test_numpy_values(self):
      input_data = {
          "img1": np.array([[0, 1], [1, 2]]),
          "img2": np.array([[0, 1], [1, 2]]),
      }
      result = ConcatItemsd(keys=["img1", "img2"], name="cat_img")(
          input_data
      )
      self.assertTrue("cat_img" in result)
      result["cat_img"] += 1
      np.testing.assert_allclose(
          result["img1"], np.array([[0, 1], [1, 2]])
      )
      np.testing.assert_allclose(
          result["cat_img"], np.array([[1, 2], [2, 3], [1, 2], [2, 3]])
      )
  
file_path: MONAI/tests/test_concat_itemsd.py
imports: from __future__ import annotations
  import unittest
  import numpy
  import torch
  from monai.data import MetaTensor
  from monai.transforms import ConcatItemsd
  from tests.utils import assert_allclose
label_desc: Use image node_id 3 for calling the TestConcatItemsd obj's underlying member method code with example usage: obj.test_numpy_values() without return types