2 (r7rs, 4.2.2. Binding constructs, p. 16)
6 2 : Let({{x,2},{y,3}}, x*y)
9 3 : Let({x=2,y=3}, x*y)
12 4 : Let({x=2, y=3}, Let({x=7, z=x+y}, z*x))
15 5 : Let({x=2, y =3},{x=7, z=x+y}, z*x)
20 6 : Let({x=2, y=3}, Let({x=7}, Let({z=x+y}, z*x)))
23 7 : Let({x=2, y=3}, {x=7}, {z=x+y}, z*x)
32 myIsEven = Function(n, If(n==0, True, myIsOdd(n + -1)));
33 myIsOdd = Function(n, If(n==0, False, myIsEven(n + -1)));
38 (http://stackoverflow.com/a/15006018)