code: def check_serializable(cls):
      
      if is_named_tuple(cls):
          # This case works.
          return
      if not hasattr(cls, "__new__"):
          print("The class {} does not have a '__new__' attribute and is "
                "probably an old-stye class. Please make it a new-style class "
                "by inheriting from 'object'.")
          raise RayNotDictionarySerializable("The class {} does not have a "
                                             "'__new__' attribute and is "
                                             "probably an old-style class. We "
                                             "do not support this. Please make "
                                             "it a new-style class by "
                                             "inheriting from 'object'."
                                             .format(cls))
      try:
          obj = cls.__new__(cls)
      except Exception:
          raise RayNotDictionarySerializable("The class {} has overridden "
                                             "'__new__', so Ray may not be able "
                                             "to serialize it efficiently."
                                             .format(cls))
      if not hasattr(obj, "__dict__"):
          raise RayNotDictionarySerializable("Objects of the class {} do not "
                                             "have a '__dict__' attribute, so "
                                             "Ray cannot serialize it "
                                             "efficiently.".format(cls))
      if hasattr(obj, "__slots__"):
          raise RayNotDictionarySerializable("The class {} uses '__slots__', so "
                                             "Ray may not be able to serialize "
                                             "it efficiently.".format(cls))
docs: Throws an exception if Ray cannot serialize this class efficiently.
  
      Args:
          cls (type): The class to be serialized.
  
      Raises:
          Exception: An exception is raised if Ray cannot serialize this class
              efficiently.