(define sum-of-divisors
(lambda (n)
(define sum-from-plus
(lambda (low addend)
(if (> low n)
_________
_________ )))
(sum-from-plus 1 0)))
Q: When does the process stop?
A: When low > n.
Notice that the name n, introduced in the body of sum-of-divisors, is available in the body of the internal (nested) procedure sum-from-plus.