anchor.diff:  (define-presentation-type directory-stack () :inherit-from 'expression)
   (define-presentation-type bytes () :inherit-from 'integer)
   (define-presentation-type lisp-memory-usage () :inherit-from 'bytes)
  +
  +(define-presentation-type package () :inherit-from 'expression)
  +(define-presentation-method presentation-typep (object (type package))
  +  (typep object 'package))
  +
  +(define-presentation-type package-name () :inherit-from 'string)
  +(define-presentation-method presentation-typep (object (type package-name))
  +  (find-package 'object))
  +    
  +
   
   ;;; Presentation methods
   
  
positive.code:              (symbolp (second b)))
      (setf b (second b)))
    (unless (and (symbolp a) (symbolp b))
      (return-from symbol< (string< (princ-to-string a)
                                    (princ-to-string b))))
    (cond ((not (eq (symbol-package a)
                    (symbol-package b)))
           (string< (package-name (symbol-package a))
  
negative.code:       (setf gfs (append gfs (x-specializer-direct-generic-functions x))))
      (remove-duplicates gfs)))
  
  (defun not-really-symbol< (a b)
    (when (and (consp a)
               (second a)
               (symbolp (second a)))
  