code: def test_serialize_multi_index():
      pdf = pd.DataFrame(
          {
              "a": [4, 17, 4, 9, 5],
              "b": [1, 4, 4, 3, 2],
              "x": np.random.normal(size=5),
          }
      )
      gdf = cudf.DataFrame.from_pandas(pdf)
      gdg = gdf.groupby(["a", "b"]).sum()
      multiindex = gdg.index
      outindex = cudf.core.multiindex.MultiIndex.deserialize(
          *multiindex.serialize()
      )
      assert_eq(multiindex, outindex)
  
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 8 for calling a global function with example usage: test_serialize_multi_index() without return types