add o+ Chap04 p62 L5
add o- Chap04 p63 L2
add addtup Chap04 p66 L6
add o* (omultiply) Chap04 p67 L3
add tup+ Chap04 p70 L6
modify tup+ Chap04 p73 L1 (left)
modify tup+ Chap04 p73 L1 (right)