class_docstr: RoI pooling over a set of 2d planes.
class_docstr_tok: ["RoI","pooling","over","a","set","of","2d","planes","."]
code: def backward(self, indexes, grad_outputs):
      (bottom_rois,) = self.get_retained_inputs()
      (gtop_data,) = grad_outputs
  
      f = ROIPooling2DGrad(
          self.outh,
          self.outw,
          self.spatial_scale,
          self._bottom_data_shape,
          self.argmax_data,
      )
      return f.apply((bottom_rois, gtop_data))
  
imports: import numpy
  import six
  from chainer.backends import cuda
  from chainer import function_node
  from chainer.utils import type_check
label_desc: Use image node_id 5 for calling the ROIPooling2D obj's underlying member method code with example usage: obj.backward(indexes, grad_outputs) and returns: f