code: def test_set_core_num(self):
      _, core_num = get_node_and_core_number()
  
      set_core_number(core_num + 1)
  
      _, new_core_num = get_node_and_core_number()
  
      assert new_core_num == core_num + 1, (
          "set_core_num failed, set the core"
          " number to be {} but got {}".format(
              core_num + 1, new_core_num
          )
      )
  
      set_core_number(core_num)
  
imports: import pytest
  from bigdl.dllib.utils.common import get_node_and_core_number
  from test.bigdl.test_zoo_utils import ZooTestCase
  from bigdl.dllib.utils.file_utils import set_core_number
label_desc: Use image node_id 1 for calling the TestUtil obj's underlying member method code with example usage: obj.test_set_core_num() without return types