anchor.diff:  
   Without initialization.
   
  +Convenient copier.
  +
  +    (defun birthday (person)
  +      (copy-person person :age (1+ (person-age person))))
  +
  +    (birthday *)
  +    => #.(PERSON \"Common Lisp\" 34)
  +
  +Load form.
  +
   Printer.
   
       (defconstructor person
  
positive.code: 
      (person \"Common Lisp\" 33)
      => #.(PERSON \"Common Lisp\" 33)
  
  Convenient copier.
  
      (defun birthday (person)
        (copy-person person :age (1+ (person-age person))))
  
      (birthday *)
      => #.(PERSON \"Common Lisp\" 34)
  
  Pattern matching.
  
  
negative.code: some or all of its slots." type-name)
           (,type-name ,@slot-names))
  
         ;; Define a load form.
         (defmethod make-load-form ((self ,type-name) &optional env)
           (declare (ignore env))
           (list ',type-name
                 ,@(loop for reader in readers
                         collect `(,reader self))))
  
         (defmethod constructor-len ((x ,type-name))
           ,(length readers))
  
  