code: def test_symbol_pickle():
      mlist = [models.mlp2()]
      data = pkl.dumps(mlist)
      mlist2 = pkl.loads(data)
      for x, y in zip(mlist, mlist2):
          assert x.tojson() == y.tojson()
  
imports: import copy
  import sys
  import os
  import logging
  import re
  import json
  import mxnet
  import numpy
  from common import assertRaises, models, TemporaryDirectory
  from mxnet.base import NotImplementedForSymbol
  from mxnet.test_utils import discard_stderr, rand_shape_nd, use_np, environment
  from mxnet.util import np_shape
  import pickle
label_desc: Use image node_id 7 for calling a global function with example usage: test_symbol_pickle() without return types