There are three exceptional situations, which you must handle separately
有三种例外的状况，您必须对其单独处理
ValueIs avoids all of these problems by encapsulating what we really want each class to handle separately: checking whether an instance of the class contains the given value.
value Is通过封装我们真正希望每个类单独处理的内容：检查类的一个实例是否包含给定的值，以避开所有这些问题。
This section addresses these requirements separately, because different teams will probably handle the hands-on work for each side.
此部分将分开处理这些需求，因为可能将由不同的团队处理每个方面的实际工作。
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