code: def forward_expected(self, inputs):
      (x,) = inputs
      y = numpy.empty((2, 3, 2, 2), dtype=self.dtype)
      for k in six.moves.range(2):
          for c in six.moves.range(3):
              xx = x[k, c]
              y[k, c] = (
                  numpy.array(
                      [
                          [xx[0:2, 0:2].sum(), xx[0:2, 1:3].sum()],
                          [xx[1:4, 0:2].sum(), xx[1:4, 1:3].sum()],
                      ]
                  )
                  / 9
              )
      return (y,)
  
imports: import unittest
  import numpy
  import six
  import chainer
  from chainer.backends import cuda
  from chainer import functions
  from chainer import testing
  from chainer.testing import attr
  from chainer.testing import backend
label_desc: Use image node_id 4 for calling the TestAveragePooling2D obj's underlying member method code with example usage: obj.forward_expected(inputs) and returns: y