code: def _training_end(self, event):
      self._check_status_events[event.model].append(event.status)
  
imports: import random
  from collections import defaultdict, Counter
  import pytest
  from nni.mutable import SampleValidationError
  from nni.nas.execution import SequentialExecutionEngine
  from nni.nas.space import ModelStatus
  from nni.nas.strategy import Random, RegularizedEvolution, PolicyBasedRL, GridSearch, Strategy
  from nni.nas.strategy.base import StrategyStatus
  from nni.nas.strategy.middleware import Filter, Chain, Deduplication, FailureHandler, MultipleEvaluation
  from .test_sanity import named_model_space, engine, naive_policy
label_desc: Use image node_id 9 for calling the MockStrategy obj's underlying member method code with example usage: obj._training_end(event) without return types