anchor.diff:  ;;;; Some test concept implementations
   (implement-concept 
       (foobar impl-fast "FAST foobar implementation")
  -  (x y)
  +  ( (x "") 
  +    (y "") ) 
     (+ x y))
   
   (implement-concept 
       (foobar impl-generic "GENERIC foobar implementation" :default-implementation t)
  -  (x y)
  +  ( (x "") 
  +    (y "") )
     (- x y))
   
   
  
positive.code:       (append positional 
  	      (when rest (list '&rest (caar rest)))
  	      (when named (list '&key)) named
  	      others)))
    
    
  ;;;;
  
negative.code: ;;;; Returns the head of hte list, all but the last element
  (defun all-but-last (list)
    (subseq list 0 (1- (length list))))
  
  
  ;;;;
  ;;;; "normalizes" arguments from the result of parsing a documented lambda list
  