code: def forward_expected(self, inputs):
      (x,) = inputs
      y_expect = numpy.mean(
          x.astype(numpy.float64), self.axis, keepdims=self.keepdims
      ).astype(self.dtype)
      return (utils.force_array(y_expect),)
  
imports: import unittest
  import numpy
  import six
  from chainer import functions
  from chainer import testing
  from chainer.testing import attr
  from chainer import utils
label_desc: Use image node_id 4 for calling the TestAverageOverflowingSum obj's underlying member method code with example usage: obj.forward_expected(inputs) and returns: utils