code: def compute_default_choice(self):
          
  
          choices = self.choices
  
          if len(choices) == 0:
              return None
  
          high_choice = max(choices, key=lambda choice: choice.performance)
          self.redis.hset(EXPERIMENT_REDIS_KEY_TEMPLATE % self.name, "default-choice", high_choice.name)
          self.refresh()
          return high_choice
docs: Computes and sets the default choice