A closed generic type is a type declaration where a particular type is specified for a type parameter.
封闭式泛型类型是为类型参数指定特定类型的类型声明。
This is true even if the enclosing generic type is a closed constructed type.
即使封闭泛型类型为封闭构造类型，也是如此。
A generic type definition is not assignable from a closed constructed type.
泛型类型定义不可以从封闭构造的类型赋值。
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