code: def create_new(cls, oldvalue, *args):
      "Raise  if the old value already exists"
      if oldvalue is not None:
          raise AlreadyExistsException('%r already exists' % (oldvalue,))
      return cls.create_instance(*argsf create_new(cls, oldvalue, *args):
      "Raise  if the old value already exists"
      if oldvalue is not None:
          raise AlreadyExistsException('%r already exists' % (oldvalue,))
      return cls.create_instance(*args)
docs: Raise  if the old value already exists