code: def test_custom_objective(self):
      self.run_custom_objective()
  
imports: import json
  import os
  import tempfile
  import numpy
  import pytest
  import xgboost
  from xgboost import testing
  from xgboost.testing.updater import ResetStrategy
label_desc: Use image node_id 6 for calling the TestModels obj's underlying member method code with example usage: obj.test_custom_objective() without return types