remove the type in object test
And replace by "unavailability_message_attached: unavailable implies attached unavailablity_message as m and then
    m.count > 0 "

I consider harmful to put the type in object test local when this is not needed.
because if one day, we change `unavailablity_message' to be a READABLE_STRING_32 ... your code is broken

putting type in object test local .. is similar to use (now deprecated)  reverse assignment attempt.