code: def _retrieve_best_trial(experiment: Experiment) -> Optional[Trial]:
      """Constructs the view of the best trial if there is one"""
      if not experiment.stats.trials_completed:
          return None
  
      return experiment.get_trial(uid=experiment.stats.best_trials_id)
  
file_path: orion/src/orion/serving/experiments_resource.py
imports: import json
  from typing import Optional
  from falcon import Request, Response
  from orion.core.worker.experiment import Experiment
  from orion.core.worker.trial import Trial
  from orion.serving.parameters import retrieve_experiment, verify_query_parameters
  from orion.serving.responses import build_experiment_response, build_experiments_response
label_desc: Use image node_id 4 for calling a global function with example usage: _retrieve_best_trial(experiment) and returns: experiment, None