class_docstr: Padding of an array.
class_docstr_tok: ["Padding","of","an","array","."]
code: def backward(self, inputs, grad_outputs):
      (gy,) = grad_outputs
      in_shape = self.inputs[0].shape
      if self.pad_bw.ndim == 1:
          self.pad_bw = numpy.tile(self.pad_bw, (len(in_shape), 1))
      input_idxs = tuple(
          slice(p[0], p[0] + dim)
          for dim, p in zip(in_shape, self.pad_bw)
      )
      return (gy[input_idxs],)
  
file_path: chainer/chainer/functions/array/pad.py
imports: import numpy
  from chainer import backend
  from chainer import function_node
  from chainer.utils import type_check
label_desc: Use image node_id 4 for calling the Pad obj's underlying member method code with example usage: obj.backward(inputs, grad_outputs) and returns: gy