Playing with UnboundedCounter
Initially: an unbounded counter with value 0
After 20 up's: an unbounded counter with value 20
After 3 down's: an unbounded counter with value 17

Playing with UpperBoundedCounter
Initially: A upper-bounded counter with value 0 and limit 10
After 20 up's: A upper-bounded counter with value 10 and limit 10
After 3 down's: A upper-bounded counter with value 7 and limit 10