completed step 7 of TDD part 3
 completed step 8 of TDD part 3
 completed step 10 of TDD part 3
 completed step 11 of TDD part 3
 completed step 11b of TDD part 3
 completed step 12 of TDD part 3
 completed step 13 of TDD part 3
 completed step 14 of TDD part 3
 completed step 14b of TDD part 3