code: def objective_function(para):
      score = -para["x1"] * para["x1"]
      return score
  
file_path: Hyperactive/tests/test_early_stop.py
imports: import time
  import pytest
  import numpy
  from sklearn.datasets import load_breast_cancer
  from sklearn.model_selection import cross_val_score
  from sklearn.tree import DecisionTreeClassifier
  from hyperactive import Hyperactive
  from hyperactive.optimizers import RandomSearchOptimizer, HillClimbingOptimizer
label_desc: Use image node_id 1 for calling a global function with example usage: objective_function(para) and returns: score