Okay, I'm really hoping this is the source of the confusion, otherwise I need to go get another cup of coffee. :-)

> `StaticObject` has a `respondsTo($method, $visibility)` so this cannot have a `respondsTo($object, $method, $visibility)`.

Yeah, I said change `callable()` to `isCallable()`, not `callable()` to `respondsTo()`. Hopefully now this all makes sense. :-)