side to know the element type anyway. So, I apologize for sending us down a useless side path. We may as well stick to the function signature as shown in the v15 patch --- although maybe variadic any is still worthwhile so that an unrecognized field name doesn't need to be a hard error?
Variadic is nearly done. This issue was the main blocking point. I can go back to array_in() as we know that code works.