code: def onnx_non_max_suppression_backward(
      inputs,
      max_output_boxes_per_class=None,
      iou_threshold=None,
      score_threshold=None,
  ):
      """
      Args:
        inputs (list of nn.Variable): Incomming grads/inputs to/of the forward function.
        kwargs (dict of arguments): Dictionary of the corresponding function arguments.
  
      Return:
        list of Variable: Return the gradients wrt inputs of the corresponding function.
      """
      dy = inputs[0]
      x0 = inputs[1]
      raise NotImplementedError(
          "onnx_non_max_suppression_backward is not implemented."
      )
  
label_desc: Use image node_id 1 for calling a global function with example usage: onnx_non_max_suppression_backward(inputs, max_output_boxes_per_class, iou_threshold, score_threshold) without return types