Completed ex15, study drill 8
Completed ex16
Completed ex16, study drill 2
Completed ex16, study drill 3
Completed ex16, study drill 5
Completed ex17
Completed ex17, stduy drill 1
Complete ex18
Added function checklist
Completed ex19
Completed ex19, study drill 1
Made a start on ex19, study drill 3
Completed ex19, study drill 3
Completed ex20
Completed ex20
Started ex20, study drill 1
 Completed ex20, study drill 1
 Completed ex20, study drill 2
 Completed ex21
 Completed ex24