anchor.diff:    (let ((account (stored-account account-id (storage bank))))
       (withdraw account amount)))
   
  -;;; Storage Adaptor Implementation
  +;;; Outer Hexagon - Storage Adapter
   
   (defmethod stored-account (account-id (storage hash-table))
     (gethash account-id storage))
  
positive.code: 
  (defgeneric (setf stored-account) (account account-id storage))
  
  ;;; Application
  
  (defclass account ()
    ((balance :initarg :balance :accessor balance)))
  
  (defmethod withdraw ((account account) amount)
    (decf (balance account) amount))
  
  (defclass bank ()
    ((storage :initarg :storage :reader storage)))
  
negative.code: 
  (in-package #:grok-arch-hexagonal-hexarch2)
  
  ;;; Inner Hexagon - Domain
  
  (defclass account ()
    ((balance :initarg :balance :accessor balance)))
  
  (defmethod withdraw ((account account) amount)
    (decf (balance account) amount))
  
  ;;; Inner Hexagon - Storage Port
  
  (defclass storage ()
    ())
  