code: def check_forward(self, space_data, depth_data):
      space = chainer.Variable(space_data)
      s2d = functions.space2depth(space, self.r)
      s2d_value = cuda.to_cpu(s2d.data)
  
      self.assertEqual(s2d_value.dtype, self.dtype)
      self.assertEqual(s2d_value.shape, (2, 8, 3, 2))
  
      s2d_expect = depth_data
  
      testing.assert_allclose(s2d_value, s2d_expect)
  
imports: import unittest
  import numpy
  import chainer
  from chainer.backends import cuda
  from chainer import functions
  from chainer import gradient_check
  from chainer import testing
  from chainer.testing import attr
label_desc: Use image node_id 2 for calling the TestSpace2Depth obj's underlying member method code with example usage: obj.check_forward(space_data, depth_data) without return types