code: def test_sens_expand_reduce(self, test_data, sens):
      result = sensitivity_map_reduce(test_data, sens)
      result = sensitivity_map_expand(result, sens)
      self.assertEqual(result.shape, test_data.shape)
  
file_path: MONAI/tests/test_recon_net_utils.py
imports: from __future__ import annotations
  import unittest
  import torch
  from parameterized import parameterized
  from monai.apps.reconstruction.networks.nets.utils import complex_normalize, divisible_pad_t, inverse_divisible_pad_t, reshape_batch_channel_to_channel_dim, reshape_channel_complex_to_last_dim, reshape_channel_to_batch_dim, reshape_complex_to_channel_dim, sensitivity_map_expand, sensitivity_map_reduce
  from tests.utils import assert_allclose
label_desc: Use image node_id 4 for calling the TestReconNetUtils obj's underlying member method code with example usage: obj.test_sens_expand_reduce(test_data, sens) without return types