I am using `Named` as an argument. In structural type systems, what matters is the type structure. It's not duck typing because it's checked at compile-time. I

I am using `Named` as an argument. In structural type systems, what matters is the type structure. It's not duck typing because it's checked at compile-time. If I change the type of "Named" to have the fields `firstName` and `lastName` of type string, accessing any other property inside `f` (like `obj.nonExisting`) or passing objects that don't have those fields.