code: def check_deleted(self, backend_config):
      layer, hook = self.layer, self.hook
      layer.add_hook(hook)
      layer.to_device(backend_config.device)
      x = backend_config.get_array(self.x)
  
      with chainer.using_device(backend_config.device):
          y1 = layer(x).array
          with chainer.using_config("train", False):
              y2 = layer(x).array
          layer.delete_hook(hook.name)
          assert not hasattr(layer, hook.vector_name)
          y3 = layer(x).array
      y1, y2, y3 = _cpu._to_cpu(y1), _cpu._to_cpu(y2), _cpu._to_cpu(y3)
      assert not numpy.array_equal(y1, y3)
      assert not numpy.array_equal(y2, y3)
  
imports: import copy
  import os
  import unittest
  import numpy
  import pytest
  import chainer
  from chainer.backends import _cpu
  from chainer.link_hooks.spectral_normalization import SpectralNormalization
  import chainer.links
  from chainer import serializers
  from chainer import testing
  from chainer.testing import attr
  from chainer.testing.backend import BackendConfig
  from chainer import utils
label_desc: Use image node_id 7 for calling the BaseTest obj's underlying member method code with example usage: obj.check_deleted(backend_config) without return types