code: def test_im2col_gpu(self):
      self.check_im2col(*self.params, gpu=True)
  
imports: import unittest
  import numpy
  from six import moves
  from chainer.backends import cuda
  from chainer import testing
  from chainer.testing import attr
  from chainer.utils import conv
label_desc: Use image node_id 4 for calling the TestIm2Col obj's underlying member method code with example usage: obj.test_im2col_gpu() without return types