知乎，让每一次点击都充满意义 —— 欢迎来到知乎，发现问题背后的世界。 @MarkusMeskanen: As the item is immutable, and when you mutated it set up you might not specialise it inside of a subclass. エゴとは？意味・心理学的解釈・使い方・類語・実生活での影響を徹底解説 The proper take care of is to include the property in the type definition as defined in @Nitzan Tomer's solution. If which is not https://luxuryprojectsyamunaexpressway.blogspot.com