code: def _to_tensor(self):
      input = self.model_inputs[0].zvalue
      assert (
          len(self.onnx_attr["axes"]) == 1
      ), "we only support axes with 1 elements for now"
      axes = self.onnx_attr["axes"][0]
      keepdims = True if self.onnx_attr["keepdims"] == 1 else False
      return autograd.sum(input, axis=int(axes), keepDims=keepdims)
  
file_path: analytics-zoo/pyzoo/zoo/pipeline/api/onnx/mapper/reducesum.py
imports: from zoo.pipeline.api.onnx.mapper.operator_mapper import OperatorMapper
  import zoo.pipeline.api.autograd
  from zoo.pipeline.api.onnx.onnx_helper import OnnxHelper
  import zoo.pipeline.api.keras.layers
label_desc: Use image node_id 3 for calling the ReduceSumMapper obj's underlying member method code with example usage: obj._to_tensor() and returns: autograd