anchor.diff:  ;;; 23.7.1 Defining Presentation Translators
   
   (defclass presentation-translator ()
  -  ((name :reader name :initarg :name)
  +  ((name :reader name :initarg :name)   
      (from-type :reader from-type :initarg :from-type)
      (to-type :reader to-type :initarg :to-type)
      (gesture :reader gesture :initarg :gesture)
  
positive.code: 
  ;;; This lives in a command table
  
  (defclass translator-table ()
    ((translators :accessor translators :initarg :translators
  		:initform (make-hash-table :test #'eq)
  
negative.code: 
  
  (defun find-presentation-translators (from-type to-type command-table)
    (let* ((command-table (find-command-table command-table))	 
  	 (from-name (presentation-type-name from-type))
  	 (to-name (presentation-type-name to-type))
  	 (cached-translators (gethash (cons from-name to-name)
  