class_docstr: Im2Col function.
code: def backward(self, indexes, grad_outputs):
      return Im2ColGrad(
          (self.kh, self.kw),
          (self.sy, self.sx),
          (self.ph, self.pw),
          self.cover_all,
          (self.dy, self.dx),
          self.inputs[0].shape,
      ).apply(grad_outputs)
  
imports: import numpy
  from chainer import function_node
  from chainer.utils.conv import col2im_cpu
  from chainer.utils.conv import col2im_gpu
  from chainer.utils.conv import im2col_cpu
  from chainer.utils.conv import im2col_gpu
  from chainer.utils import type_check
label_desc: Use image node_id 4 for calling the Im2Col obj's underlying member method code with example usage: obj.backward(indexes, grad_outputs) and returns: Im2ColGrad