anchor.diff:          (:flag
            `((T)))
           (:bool
  -         `((T ,(format NIL "~a~a" prefix name)))))))
  +         `((T ,(format NIL "~a~a" prefix name))))
  +        ((:arg :arg= :arg.)
  +         (unless (or (assoc :flag options) (assoc :bool options))
  +           `((null)))))))
   
   (defgeneric location (thing)
     (:method ((pathname pathname))
  
positive.code:             (progn
                (ensure-directories-exist ,new)
                (uiop:chdir ,new)
                (let ((*default-pathname-defaults* ,new))
                  ,@body))
           (uiop:chdir ,old)))))
  
  (defun minimal-shell-namestring (pathname)
  
negative.code:           ,@(loop for arg in req unless (front-arg-p arg) collect (parse-rargdef arg))
            ,@(loop for arg in opt unless (front-arg-p arg) collect (parse-oargdef arg)))))))
  
  (defmacro %opt (options &rest forms)
    `(let ((args (or ,@(loop for option in (if (listp options) options (list options))
                             collect `(assoc ,option options)))))
       (when args
         ,@forms)))
  
  