code: def test_single_numpy(self):
      input_data = {"img": np.array([[0, 1], [1, 2]])}
      result = ConcatItemsd(keys="img", name="cat_img")(input_data)
      result["cat_img"] += 1
      np.testing.assert_allclose(
          result["img"], np.array([[0, 1], [1, 2]])
      )
      np.testing.assert_allclose(
          result["cat_img"], np.array([[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 4 for calling the TestConcatItemsd obj's underlying member method code with example usage: obj.test_single_numpy() without return types