class_docstr: Element-wise weighted sum of input arrays.
code: def backward(self, inputs, grads):
      return [w * grads[0] for w in self.weights]
  
file_path: chainerrl/chainerrl/functions/weighted_sum_arrays.py
imports: from chainer import cuda
  from chainer import function
  from chainer import utils
  from chainer.utils import type_check
label_desc: Use image node_id 4 for calling the WeightedSumArrays obj's underlying member method code with example usage: obj.backward(inputs, grads) and returns: unknown