anchor.diff:    (assert-equal '(2 8 2 4) (keep #'even '(1 2 8 2 3 4)))
     (assert-equal '() (keep #'even '(5 7 3)))
     (assert-equal '(2 12 72 6) (keep #'even '(2 12 72 6)))
  -  ;;; same tests but for vectors
  +  ;; Same tests but for vectors.
     (assert-equalp #() (keep 7 #()))
     (assert-equalp #() (keep #'even #()))
     (assert-equalp #(2 8 2 4) (keep #'even #(1 2 8 2 3 4)))
     (assert-equalp #() (keep #'even #(5 7 3)))
     (assert-equalp #(2 12 72 6) (keep #'even #(2 12 72 6))))
   
  -;; member does not work on vectors (what is the tail of a vector?)
  +;;; Member does not work on vectors (what is the tail of a vector?).
   (deftest mem (hof)
     (assert-false (mem 7 '()))
     (assert-false (mem #'even '()))
  
positive.code:   (assert-eql 0 (count #'even '(1 3 71 21)))
    (assert-eql 3 (count 5 '(1 5 3 2 5 7 5)))
    (assert-eql 4 (count #'even '(1 6 3 2 2 4)))
    ;;; same tests but for vectors
    (assert-eql 0 (count 2 #()))
    (assert-eql 0 (count #'even #()))
    (assert-eql 0 (count #'even #(1 3 71 21)))
  
negative.code: (deftest withs (binding)
    (assert-eql 12 (withs (x 5 y (+ x 3)) (+ y 4))))
  
  ;;;; Tests for hof.
  
  (deftest testify (hof)
    (assert-true  (funcall (testify 5) 5))
  