code: def test_serialize():
      reset_envs()
      os.environ["DGL_DIST_MODE"] = "distributed"
      from dgl.distributed.rpc import (
          deserialize_from_payload,
          serialize_to_payload,
      )
  
      SERVICE_ID = 12345
      dgl.distributed.register_service(
          SERVICE_ID, MyRequest, MyResponse
      )
      req = MyRequest()
      data, tensors = serialize_to_payload(req)
      req1 = deserialize_from_payload(MyRequest, data, tensors)
      req1.foo(req1.x, req1.y)
      assert req.x == req1.x
      assert req.y == req1.y
      assert F.array_equal(req.z, req1.z)
  
      res = MyResponse()
      data, tensors = serialize_to_payload(res)
      res1 = deserialize_from_payload(MyResponse, data, tensors)
      assert res.x == res1.x
  
imports: import multiprocessing
  import os
  import socket
  import time
  import unittest
  import backend
  import dgl
  import pytest
  from numpy.testing import assert_array_equal
  from utils import generate_ip_config, reset_envs
label_desc: Use image node_id 7 for calling a global function with example usage: test_serialize() without return types