anchor.diff:      "The reduce function applies uses a supplied
        binary function to combine the elements of a
        list from left to right."
  -  (assert-equal ___  (reduce #'+ '(1 2 3 4)))
  -  (assert-equal ___ (reduce #'expt '(2 3 2))))
  +  (assert-equal 10  (reduce #'+ '(1 2 3 4)))
  +  (assert-equal 64 (reduce #'expt '(2 3 2))))
   
   
   (define-test test-reduce-right-to-left
       "The keyword :from-end allows us to apply
        reduce from right to left."
  -  (assert-equal ___ (reduce #'+ '(1 2 3 4) :from-end t))
  -  (assert-equal ___ (reduce #'expt '(2 3 2) :from-end t)))
  +  (assert-equal 10 (reduce #'+ '(1 2 3 4) :from-end t))
  +  (assert-equal 512 (reduce #'expt '(2 3 2) :from-end t)))
   
   
   (define-test test-reduce-with-initial-value
       "We can supply an initial value to reduce."
  -  (assert-equal ___ (reduce #'expt '(10 21 34 43) :initial-value 1))
  -  (assert-equal ___ (reduce #'expt '(10 21 34 43) :initial-value 0)))
  +  (assert-equal 1 (reduce #'expt '(10 21 34 43) :initial-value 1))
  +  (assert-equal 0 (reduce #'expt '(10 21 34 43) :initial-value 0)))
   
   
   (defun WRONG-FUNCTION-2 (a b) (a))
  
positive.code:     "The mapcar function can be applied to
       more than one list. It applies a function
       to successive elements of the lists."
    (assert-equal ____ (mapcar #'* '(1 2 3) '(4 5 6)))
    (assert-equal ____ (mapcar #'list '("lisp" "are") '("koans" "fun"))))
  
  
  (define-test test-transpose-using-mapcar
      "Replace WRONG-FUNCTION with the correct function (don't forget
       the #') to take the 'transpose'."
    (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)) 
  
negative.code:      insert the correct function names, instead of INCORRECT-FUNCTION-X
       to define an inner product."
    (defun inner (x y) 
      (reduce #'+ (mapcar #'* x y)))
    (assert-equal 32 (inner '(1 2 3) '(4 5 6)))
    (assert-equal 310 (inner '(10 20 30) '(4 3 7))))
  