Readonly<Type>
构造一个将 Type 的所有属性设置为 readonly 的类型，这意味着构造类型的属性不能重新分配。
Constructs a type with all properties of Type set to readonly, meaning the properties of the constructed type cannot be reassigned.
构造一个将 Type 的所有属性设置为 readonly 的类型，这意味着构造类型的属性不能重新分配。
Constructs a type with all properties of Type set to readonly, meaning the properties of the constructed type cannot be reassigned.