anchor.diff:    (with-gensyms (temp)
       `(let ((,temp (make-array ,(length values))))
          (declare (dynamic-extent ,temp))
  -       ,@(loop for i from 0 
  +       ,@(loop for i from 0
                  for v in values
                  collect `(setf (svref ,temp ,i) ,v))
          ;; Keep compiler quiet.
  
positive.code: (defmacro sort-values (pred &rest values)
    "Sort VALUES with PRED and return as multiple values.
  
  Equivalent to 
  
      (values-list (sort (list VALUES...) pred))
  
  
negative.code: (defmacro ecase-let ((var expr) &body cases)
    "Like (let ((VAR EXPR)) (ecase VAR ...)), with VAR read-only."
    `(let1 ,var ,expr
       (ecase ,var
         ,@cases)))
  
  (defmacro comment (&body body)
  