@classmethod
  def _update_kind_map(cls):
    cls._kind_map[cls._get_kind()] = cls
also known as XOR
dataset/ETHPy150Open GoogleCloudPlatform/datastore-ndb-python/ndb/model.py/Model._update_kind_map--crossover with--dataset/ETHPy150Open CountZer0/PipelineConstructionSet/python/maya/site-packages/pymel-1.0.3/pymel/core/nodetypes.py/ObjectSet.getSymmetricDifference