code: def __call__(self, trial_id: str, result: dict) -> bool:
      if not self.should_stop and result["mean_accuracy"] >= 0.8:
          self.should_stop = True
      return self.should_stop
  
imports: from ray import train
  from ray import train, tune
  from ray import train, tune
  from ray import train, tune
  from ray.tune import Stopper
  from ray import train, tune
  import time
  from ray import train, tune
  from ray.tune.schedulers import AsyncHyperBandScheduler
  from ray import train, tune
  from ray import tune
label_desc: Use image node_id 2 for calling the CustomStopper obj's underlying member method code with example usage: obj.__call__(trial_id, result) and returns: self