IMO, it's better to mirror the use of the collection method inside Set::contains() instead of using in_array, since items seems to be a Collection object. You get more functionality that way and it's more Laravel-ish.
I see your suggestion. However, it's important to remember an array is a collection. No need to introduce an entire framework just to use one method.
Ah, I see that the other calls are to the Set class size and contains. I misread - I thought it was calling those on items. My bad. You are correct.
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