code: def test_model_compatibility_npz(self, backend_config):
      self.check_model_compatibility(
          backend_config,
          chainer.serializers.save_npz,
          chainer.serializers.load_npz,
      )
  
imports: import contextlib
  import os
  import tempfile
  import unittest
  import numpy
  import chainer
  from chainer import links
  from chainer import testing
label_desc: Use image node_id 4 for calling the TestDecorrelatedBatchNormalizationCompat obj's underlying member method code with example usage: obj.test_model_compatibility_npz(backend_config) without return types