anchor.diff:  ;;;       (time (setf l2 (list-to-set l2))))
   ;; (array->list array) --> (coerce array 'list)
   
  +(defun test ()
  +  (test/list-lengths)
  +  (test/list-elements))
  +
   ;;;; THE END ;;;;
  
positive.code: 
  
  
  (defun ensure-circular (list)
    "
  If list is not a circular list, then modify it to make it circular.
  
negative.code:            "PLIST-KEYS" "PLIST-REMOVE" "PLIST-GET"
             "PLIST-PUT" "PLIST-CLEANUP" "HASHED-INTERSECTION" 
             ;; "HASHED-REMOVE-DUPLICATES" moved to COM.INFORMATIMAGO.COMMON-LISP.CESARUM.SEQUENCE
             "ENSURE-LIST" "PROPER-LIST-P" "LIST-LENGTHS" "LIST-ELEMENTS"
             "ENSURE-CIRCULAR" "MAKE-CIRCULAR-LIST" "CIRCULAR-LENGTH"
             "TREE-DIFFERENCE" "REPLACE-TREE" "MAPTREE")
    (:documentation
  