code: def forward_expected(self, inputs):
      (x,) = inputs
      flip_func = getattr(numpy, "flip", functions.array.flip._flip)
      y_expected = flip_func(x, self.axis)
      return (y_expected,)
  
imports: import unittest
  import numpy
  from chainer.backends import cuda
  from chainer import functions
  from chainer import testing
  from chainer.testing import attr
  from chainer.utils import type_check
label_desc: Use image node_id 3 for calling the TestFlip obj's underlying member method code with example usage: obj.forward_expected(inputs) and returns: y_expected