Description:
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Apparently we can do cool things with `class` since 5.5, like:

    static::class  // MyNamespace\ClassC when run in A
    self::class    // MyNamespace\ClassA when run in A
    parent::class  // MyNamespace\ClassB when run in C
    MyClass::class // MyNamespace\MyClass

But there seem to be no references to it in the official documentation. There are some scattered things about it on the web, but not a lot. Is this official? Is it supported? Can this be documented?