code: def test_fillna_vertices():
      from cugraph.experimental import MGPropertyGraph
  
      df_edgelist = dask_cudf.from_cudf(
          cudf.DataFrame(
              {
                  "src": [0, 7, 2, 0, 1, 3, 1, 4, 5, 6],
                  "dst": [1, 1, 1, 3, 2, 1, 6, 5, 6, 7],
                  "val": [1, None, 2, None, 3, None, 4, None, 5, None],
              }
          ),
          npartitions=2,
      )
  
      df_props = dask_cudf.from_cudf(
          cudf.DataFrame(
              {
                  "id": [0, 1, 2, 3, 4, 5, 6, 7],
                  "a": [0, 1, None, 2, None, 4, 1, 8],
                  "b": [None, 1, None, 2, None, 3, 8, 9],
              }
          ),
          npartitions=2,
      )
  
      pG = MGPropertyGraph()
      pG.add_edge_data(df_edgelist, vertex_col_names=["src", "dst"])
      pG.add_vertex_data(df_props, vertex_col_name="id")
  
      pG.fillna_vertices({"a": 2, "b": 3})
  
      assert (
          not pG.get_vertex_data(columns=["a", "b"])
          .compute()
          .isna()
          .any()
          .any()
      )
      assert (
          pG.get_edge_data(columns=["val"]).compute().isna().any().any()
      )
  
      expected_values_prop_a = [
          0,
          1,
          2,
          2,
          2,
          4,
          1,
          8,
      ]
      assert pG.get_vertex_data(columns=["a"])[
          "a"
      ].compute().values_host.tolist() == (expected_values_prop_a)
  
      expected_values_prop_b = [
          3,
          1,
          3,
          2,
          3,
          3,
          8,
          9,
      ]
      assert pG.get_vertex_data(columns=["b"])[
          "b"
      ].compute().values_host.tolist() == (expected_values_prop_b)
  
imports: import gc
  import pytest
  import pandas
  import numpy
  import cudf
  import cugraph
  import dask_cudf
  import cupy
  import cugraph.dask
  from cupy.testing import assert_array_equal
  from cudf.testing import assert_frame_equal, assert_series_equal
  from pylibcugraph.testing.utils import gen_fixture_params_product
  from cugraph.dask.common.mg_utils import is_single_gpu
  from cugraph.datasets import cyber, netscience
label_desc: Use image node_id 29 for calling a global function with example usage: test_fillna_vertices() without return types