code: def check_double_backward(self, xs_data, g_data, ggs_data):
      def func(*xs):
          return functions.stack(xs, self.axis)
  
      gradient_check.check_double_backward(
          func, xs_data, g_data, ggs_data, dtype=numpy.float64
      )
  
imports: import unittest
  import numpy
  import chainer
  from chainer import backend
  from chainer.backends import cuda
  from chainer import functions
  from chainer import gradient_check
  from chainer import testing
  from chainer.testing import attr
  import chainerx
label_desc: Use image node_id 10 for calling the TestStack obj's underlying member method code with example usage: obj.check_double_backward(xs_data, g_data, ggs_data) and returns: functions