code: def test_kcore(self):
      if "kcore" in get_unity().list_toolkit_functions():
          m = tc.kcore.create(self.graph)
          print(m)
          m.summary()
          biggest_core = (
              m.core_id.groupby("core_id", tc.aggregate.COUNT)
              .topk("Count")
              .head(1)
          )
          self.assertEqual(biggest_core["core_id"][0], 6)
          self.assertEqual(biggest_core["Count"][0], 4492)
          self.__test_model_save_load_helper__(m)
  
imports: from __future__ import print_function
  from __future__ import division
  from __future__ import absolute_import
  from .None import util
  import unittest
  import pandas
  from pandas.util.testing import assert_frame_equal
  import turicreate
  from turicreate._connect.main import get_unity
  from turicreate.toolkits._main import ToolkitError
  from turicreate.data_structures.sgraph import SGraph
  from turicreate.data_structures.sframe import SFrame
  import sys
label_desc: Use image node_id 9 for calling the GraphAnalyticsTest obj's underlying member method code with example usage: obj.test_kcore() without return types