anchor.diff:  ;;;;
   ;;;; - special prompt syntax for forms not to be evaluated when a file
   ;;;;   is loaded
  -;;;;
  -;;;; - pathnames for input/output
   ;;;;
   ;;;; - capture conditions signalled?
   
  
positive.code:                            ,input))
  
  (defun call-with-input-stream (fn input)
    (cond ((typep input 'stream)
           ;; There is no way to guarantee that FILE-POSITION will work
           ;; on a stream so let's just read the entire INPUT into a
           ;; string.
           (with-input-from-string (stream (read-stream-into-string input))
             (funcall fn stream)))
          ((typep input 'string)
           (with-input-from-string (input input)
             (funcall fn input)))
          (t
  
negative.code:                             ,output))
  
  (defun call-with-output-stream (fn output)
    (cond ((streamp output)
           (funcall fn output))
          ((null output)
           (with-output-to-string (stream)
             (funcall fn stream)))
          (t
           (assert nil))))
  
  (defun write-transcript (transcript output &key update-only
                           (include-no-output update-only)
  