code: def slot(self, slot_index, marshal=None, unmarshal=None, build=None, cast=None, compress=False):
          
  
          def decorate(o):
              assert isinstance(o, PersistentMap)
              name = o.__class__.__name__
              assert slot_index not in self._index_to_slot
              assert name not in self._name_to_slot
              o._zlmdb_slot = slot_index
              o._zlmdb_marshal = marshal
              o._zlmdb_unmarshal = unmarshal
              o._zlmdb_build = build
              o._zlmdb_cast = cast
              o._zlmdb_compress = compress
              _slot = Slot(slot_index, name, o)
              self._index_to_slot[slot_index] = _slot
              self._name_to_slot[name] = _slot
              return o
  
          return decorate
docs: Decorator for use on classes derived from zlmdb.PersistentMap. The decorator define slots
          in a LMDB database schema based on persistent maps, and slot configuration.
  
          :param slot_index:
          :param marshal:
          :param unmarshal:
          :param build:
          :param cast:
          :param compress:
          :return: