code: def test_serialize_groupby_df():
      df = cudf.DataFrame()
      df["key_1"] = np.random.randint(0, 20, 100)
      df["key_2"] = np.random.randint(0, 20, 100)
      df["val"] = np.arange(100, dtype=np.float32)
      gb = df.groupby(["key_1", "key_2"], sort=True)
      outgb = gb.deserialize(*gb.serialize())
      expect = gb.mean()
      got = outgb.mean()
      assert_eq(got.sort_index(), expect.sort_index())
  
imports: import pickle
  import msgpack
  import numpy
  import pandas
  import pytest
  import cudf
  from cudf.testing import _utils
  from cudf.testing._utils import assert_eq
label_desc: Use image node_id 10 for calling a global function with example usage: test_serialize_groupby_df() without return types