code: def objective_function(opt):
      score = -(opt["x1"] * opt["x1"] + opt["x2"] * opt["x2"])
      return score
  
file_path: Hyperactive/tests/test_optimizers/test_optimization_strategies.py
imports: import pytest
  import numpy
  from hyperactive import Hyperactive
  from hyperactive.optimizers.strategies import CustomOptimizationStrategy
  from hyperactive.optimizers import HillClimbingOptimizer
  from ._parametrize import optimizers
label_desc: Use image node_id 1 for calling a global function with example usage: objective_function(opt) and returns: score