anchor.diff:      "We can apply a function to each member
        of a list using mapcar."
     (defun times-two (x) (* x 2))
  -  (assert-equal ____ (mapcar #'times-two '(1 2 3)))
  -  (assert-equal ____ (mapcar #'first '((3 2 1) 
  -                                      ("little" "small" "tiny") 
  +  (assert-equal '(2 4 6) (mapcar #'times-two '(1 2 3)))
  +  (assert-equal '(3 "little" "pigs") (mapcar #'first '((3 2 1)
  +                                      ("little" "small" "tiny")
                                         ("pigs" "hogs" "swine")))))
   
   
  
positive.code:   (defun WRONG-FUNCTION-1 (&rest rest) '())
    (defun transpose (L) (apply #'mapcar (cons #'WRONG-FUNCTION-1 L)))
    (assert-equal '((1 4 7)
                    (2 5 8) 
                    (3 6 9)) 
                  (transpose '((1 2 3) 
                               (4 5 6) 
                               (7 8 9))))
    (assert-equal '(("these" "pretzels" "are")
                    ("making" "me" "thirsty"))
  
negative.code:     "The reduce function combines the elements
       of a list, from left to right, by applying
       a binary function to the list elements."
    (assert-equal 10  (reduce #'+ '(1 2 3 4)))
    (assert-equal 64 (reduce #'expt '(2 3 2))))
  
  
  (define-test test-reduce-right-to-left
  