code: def convert_pad(node, **kwargs):
      
      name, input_nodes, attrs = get_inputs(node, kwargs)
  
      mxnet_pad_width = convert_string_to_list(attrs.get("pad_width"))
      onnx_pad_width = transform_padding(mxnet_pad_width)
  
      pad_mode = attrs.get("mode")
  
      if pad_mode == "constant":
          pad_value = float(attrs.get("constant_value")) \
              if "constant_value" in attrs else 0.0
          node = onnx.helper.make_node(
              'Pad',
              inputs=input_nodes,
              outputs=[name],
              mode='constant',
              value=pad_value,
              pads=onnx_pad_width,
              name=name
          )
      else:
          node = onnx.helper.make_node(
              'Pad',
              inputs=input_nodes,
              outputs=[name],
              mode=pad_mode,
              pads=onnx_pad_width,
              name=name
          )
  
      return [node]
docs: Map MXNet's pad operator attributes to onnx's Pad operator
      and return the created node.