put return-value logic back in check-value and bugfix arr[0]
put return-value logic back in check-value and bugfix arr[0]

We're not using it elsewhere anymore anyway. Also one can't index a
set(), so instead of return the first element through arr[0] we pop the
first element off of the set.

cuckoobox/cuckoo,cuckoobox/cuckoo,cuckoobox/cuckoo,cuckoobox/cuckoo,cuckoobox/cuckoo