code: def check_deleted(self, gpu):
      layer, hook = self.layer, self.hook
      layer.add_hook(hook)
      if gpu:
          with testing.assert_warns(DeprecationWarning):
              layer = layer.to_gpu()
      x = cuda.to_gpu(self.x) if gpu else self.x
  
      y1 = layer(x).array
      with chainer.using_config("train", False):
          y2 = layer(x).array
      layer.delete_hook(hook.name)
      y3 = layer(x).array
      if gpu:
          y1, y2, y3 = cuda.to_cpu(y1), cuda.to_cpu(y2), cuda.to_cpu(y3)
      assert not numpy.array_equal(y1, y3)
      assert not numpy.array_equal(y2, y3)
  
imports: import unittest
  import numpy
  import pytest
  import chainer
  from chainer.backends import cuda
  from chainer.link_hooks.weight_standardization import WeightStandardization
  import chainer.links
  from chainer import testing
  from chainer.testing import attr
label_desc: Use image node_id 6 for calling the BaseTest obj's underlying member method code with example usage: obj.check_deleted(gpu) without return types