anchor.diff:  
   (defun make-time-cache (&optional (rel-time-source
   				   (make-time-buffer)))
  -  "This make a time cache. A time cache is a lambda which each
  -   time it is called retuns the ammount of time since it was 
  -   created. 
  +  "This make an interactive time cache. A time cache is a lambda 
  +   which each time it is called retuns the ammount of time since
  +   it was created. 
      In short: a time-cache converts relative time into absolute 
      time."  
     (let ((cached-time 0))
  
positive.code:    time it is called retuns the ammount of time since it was 
     created. 
     In short: a time-cache converts relative time into absolute 
     time."  
    (let ((cached-time 0))
      (lambda (&optional command) 
        (setf cached-time (+ cached-time (funcall rel-time-source)))
  
negative.code: 
  (defun make-itime-buffer (&optional (abs-time-source
  				    #'get-internal-real-time))
    "This make an interactive time buffer. A time buffer is a lambda 
     which each time it is called retuns the ammount of time since 
     it was last called.
     It is called a time buffer as it can be imagined as
     'storing up' time for use later.
     In short: a time-buffer converts absolute time into relative
     time.
     The interactive part is that you can pass and optional command
     :reset to zero the time buffer. This can save creating a new 
     time-cache, which can be handy when you are outside the original
     context but you want to maintain the lexical scope."
    (let ((last-time (funcall abs-time-source)))
      (lambda (&optional command) 
        (case command
  