code: def test_pad(self):
      g = self.create_empty_graph()
      input = g.addInput()
      input.setType(
          input.type().with_dtype(torch.float).with_sizes([3, 320, 100])
      )
      constant = self.insert_tensor_constant(
          g, torch.ones(6, dtype=torch.long)
      )
      none = g_op(g, "prim::Constant").setType(torch.NoneType.get())
      pad = g_op(g, "Pad", input, constant, none, mode_s="constant")
      self.run_test(
          g, pad.node(), expect_tensor("Float", shape=(5, 322, 102))
      )
  
imports: import io
  import numpy
  import onnx
  import pytorch_test_common
  import torch
  from pytorch_test_common import skipIfUnsupportedMinOpsetVersion
  from torch.onnx import _constants, utils
  from torch.onnx._globals import GLOBALS
  from torch.onnx._internal import jit_utils
  from torch.testing._internal import common_utils
label_desc: Use image node_id 18 for calling the TestONNXShapeInference obj's underlying member method code with example usage: obj.test_pad() without return types