code: def check_backward(self, x_data, axis, y_grad):
      def f(x):
          return functions.normalize(x, eps=self.eps, axis=axis)
  
      gradient_check.check_backward(
          f, x_data, y_grad, **self.check_backward_options
      )
  
imports: import functools
  import itertools
  import unittest
  import numpy
  import six
  import chainer
  from chainer.backends import cuda
  from chainer import functions
  from chainer import gradient_check
  from chainer import testing
  from chainer.testing import attr
label_desc: Use image node_id 5 for calling the TestL2Normalization obj's underlying member method code with example usage: obj.check_backward(x_data, axis, y_grad) and returns: functions