anchor.diff:  
   (defclass library ()
     ((id :initarg :id
  -       :initform -1
  +       :initform nil
          :accessor library-id
          :type integer
          :documentation "The library id")
  
positive.code: 	  (loop for replace in (library-replaces library)
  	     when (requirement-matches requirement replace)
  	     do (return-from library-matches :match-replace))))))
  
negative.code: 	     :documentation "List of requirements the library suggests")
  
     (repository :initarg :repository
  	       :initform nil ;(error "Provide the library repository")
  	       :accessor library-repository
  	       :type repository
  	       :documentation "The library repository"))
  