class_docstr: Im2Col gradient function.
code: def forward(self, inputs):
      _, c, h, w = self.in_shape
      (gy,) = inputs
      n, _, out_h, out_w = gy.shape
      gy = gy.reshape(n, c, self.kh, self.kw, out_h, out_w)
      gx = _col2im(
          gy, self.sy, self.sx, self.ph, self.pw, h, w, self.dy, self.dx
      )
      return (gx,)
  
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 3 for calling the Im2ColGrad obj's underlying member method code with example usage: obj.forward(inputs) and returns: gx