code: def iter_all_volumes(self):
          '''iterate over all stored volumes'''
          for raw_volume in self._db.iterate_all():
              v = self.normalize_volume(raw_volume)
              del v['score']
              yield f iter_all_volumes(self):
          '''iterate over all stored volumes'''
          for raw_volume in self._db.iterate_all():
              v = self.normalize_volume(raw_volume)
              del v['score']
              yield v
docs: iterate over all stored volumes