code: def __prepare_bloom(self):
          
          self.__bloom = pybloom_live.ScalableBloomFilter()
          columns = [getattr(self.__table.c, key) for key in self.__update_keys]
          keys = select(columns).execution_options(stream_results=True).execute()
          for key in keys:
              self.__bloom.add(tuple(key))
docs: Prepare bloom for existing checks