@classmethod
  def _pre_delete_hook(cls, key):
    for instance in InstanceInfo.query(ancestor=key):
      instance.key.delete()
:return: a list of the production instantiations that cover a
dataset/ETHPy150Open GoogleCloudPlatform/Data-Pipeline/app/src/hadoop/datastore.py/ClusterInfo._pre_delete_hook--crossover with--dataset/ETHPy150Open nltk/nltk/nltk/parse/viterbi.py/ViterbiParser._find_instantiations