00 and 01 complete
02 complete
03 complete
04 complete
05 complete
06 complete
simplified argument defaults
07 complete
08 complete
09 complete
10 complete
11 complete
12 complete
13 tests passing
14 tests passing
15, tests passing up to 20
refactored to two_digit_handler
15 refactored again to make two_digit_handler methods shorter
15, hundreds passing
15, hundreds still passing, three and two digit handlers renamed, three digit handler refactored to be shorter