code: def _integer_scale_forward(self, gy):
      xp = backend.get_array_module(gy)
      b, c, h, w = gy.shape
      gx = gy.reshape(
          (b, c, h // self.kh, self.kh, w // self.kw, self.kw)
      )
      gx = xp.rollaxis(gx, 3, 5).sum((4, 5))
      if self.ph > 0 or self.pw > 0:
          tmp = xp.zeros(
              (b, c, h // 2 + self.ph, w // 2 + self.pw), dtype=gx.dtype
          )
          tmp[
              :,
              :,
              self.ph // 2 : -self.ph // 2,
              self.pw // 2 : -self.pw // 2,
          ] = gx
          gx = tmp
      return (gx,)
  
imports: import numpy
  import numpy.lib.stride_tricks
  from chainer import backend
  from chainer.backends import cuda
  from chainer import function_node
  from chainer.functions.pooling import pooling_2d
  from chainer.utils import conv
  from chainer.utils import type_check
label_desc: Use image node_id 2 for calling the Unpooling2DGrad obj's underlying member method code with example usage: obj._integer_scale_forward(gy) and returns: gx