C#语句修改

Question

583行是C#8.0版本支持语法，这一句怎么修改可以兼容Unity，当前不兼容Unity.
[项目源码]https://github.com/twcclegg/libphonenumber-csharp/blob/master/csharp/PhoneNumbers/BuildMetadataFromXml.cs

Answer 1

只能這樣吧

if (element.Attribute(LOCAL_ONLY) is { })
{
    var localLengths = element.Attribute(LOCAL_ONLY);
    //...
}

Answer 2

var attr=element.Attribute(LOCAL_ONLY)
if (attr){
var v=localLengths.Value;
}