anchor.diff:    (assert-equal '(((4)) ((5)))
   		(mvl (partition #'even '((1) (2) (3) (4) (5))
   				:key #'car
  +				:start 3)))
  +  ;;; same tests but for vectors
  +  (assert-equal '(() ()) (mvl (partition #'even #())))
  +  (assert-equal '(() ()) (mvl (partition 1 #())))
  +  (assert-equal '((2 4) (1 3 5)) (mvl (partition #'even #(1 2 3 4 5))))
  +  (assert-equal '((4) (5)) (mvl (partition #'even #(1 2 3 4 5) :start 3)))
  +  (assert-equal '((1 1 1) (0)) (mvl (partition 1 #(1 0 1 1))))
  +  (assert-equal '(((2) (4)) ((1) (3) (5)))
  +		(mvl (partition #'even #((1) (2) (3) (4) (5)) :key #'car)))
  +  (assert-equal '(((4)) ((5)))
  +		(mvl (partition #'even #((1) (2) (3) (4) (5))
  +				:key #'car
   				:start 3))))
   
   ;;; list
  
positive.code:   (assert-false (find #'even '()))
    (assert-false (find 5 '(2 9 1 2 7 3)))
    (assert-eql 5 (find 5 '(1 3 5 2 9 3)))
    (assert-eql 2 (find #'even '(1 3 5 2 9 3 4 6 7))))
  
  (deftest count (hof)
    (assert-eql 0 (count 2 '()))
    (assert-eql 0 (count #'even '()))
    (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))))
  
  (deftest pos (hof)
    (assert-false (pos 2 '()))
    (assert-false (pos #'even '()))
    (assert-false (pos #'even '(123 45 3 7)))
    (assert-eql 2 (pos 5 '(1 3 5 3 2 5)))
    (assert-eql 3 (pos #'even '(1 7 3 2 5 7 4 2))))
  
  (deftest mappend (hof)
    (assert-equal '() (mappend #'identity '()))
  
negative.code:   (assert-equal '(1 2 8 2) (rem 5 '(1 5 2 8 2 5)))
    (assert-equal '(5 29 5) (rem #'even '(2 5 29 5 28)))
    (assert-equal '() (rem #'even '(2 12 16 4)))
    (assert-equal '(13 5 7) (rem #'even '(13 5 7)))
    ;;; same tests but with vectors instead
    (assert-equalp #() (rem 5 #()))
    (assert-equalp #() (rem #'even #()))
    (assert-equalp #(1 2 8 2) (rem 5 #(1 5 2 8 2 5)))
    (assert-equalp #(5 29 5) (rem #'even #(2 5 29 5 28)))
    (assert-equalp #() (rem #'even #(2 12 16 4)))
    (assert-equalp #(13 5 7) (rem #'even #(13 5 7))))
  
  (deftest keep (hof)
    (assert-equal '() (keep 7 '()))
    (assert-equal '() (keep #'even '()))
    (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
    (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?)
  (deftest mem (hof)
    (assert-false (mem 7 '()))
    (assert-false (mem #'even '()))
  