code: def check_backward(self, x_data, y_grad):
      def f(x):
          return F.upsampling_2d(
              x,
              self.indices,
              ksize=self.ksize,
              stride=self.stride,
              outsize=self.in_shape[2:],
          )
  
      gradient_check.check_backward(
          f, x_data, y_grad, dtype="d", **self.check_backward_options
      )
  
imports: import unittest
  import numpy
  import chainer
  from chainer.backends import cuda
  import chainer.functions
  from chainer import gradient_check
  from chainer import testing
  from chainer.testing import attr
  from chainer.utils import conv
label_desc: Use image node_id 5 for calling the TestUpsampling2D obj's underlying member method code with example usage: obj.check_backward(x_data, y_grad) and returns: F