code: def _cleanup(self):
          '''
          Cleanup local data.
          '''
          self._declare_cb = None
          self._delete_cb = None
          super(ExchangeClass, self)._cleanup(f _cleanup(self):
          '''
          Cleanup local data.
          '''
          self._declare_cb = None
          self._delete_cb = None
          super(ExchangeClass, self)._cleanup()
docs: Cleanup local data.