Try <class> is <class>.classtype
If that really works maybe an example should be added to section
12.8.7 Class operators of the Language Guide.
While it says there:
The is operator can only be used with a class reference or a class instance
[emphasis mine]
it's not very clear how that's done, and all the current examples are with object instances.
I have discovered the InheritsFrom class function which pretty much the same as is, but works on classes as well.
Of course; they are equivalent. From the same page of the Language Guide:
The usage of this operator is as follows:
Object is Class
This expression is completely equivalent to
Object.InheritsFrom(Class)
If Object is Nil, False will be returned.
Which paragraph, incidentally, again begs the question of how "is" can be used with a class reference