code: def slots_class_sealer(fields, defaults):
      
      class __slots_meta__(type):
          def __new__(mcs, name, bases, namespace):
              if "__slots__" not in namespace:
                  namespace["__slots__"] = fields
              return type.__new__(mcs, name, bases, namespace)
  
      class __slots_base__(_with_metaclass(__slots_meta__, object)):
          __slots__ = ()
  
          def __init__(self, *args, **kwargs):
              pass
  
      return class_sealer(fields, defaults, base=__slots_base__)
docs: This sealer makes a container class that uses ``__slots__`` (it uses :func:`class_sealer` internally).
  
      The resulting class has a metaclass that forcibly sets ``__slots__`` on subclasses.