anchor.diff:                                 :output
                                  :input)))
   
  -(defun %fclose (x)
  -  (close x))
  +(defun %fclose (stream) (close stream))
  +
  +(defun %read-char (str)
  +  (alet (cl-read-char str nil 'eof)
  +    (unless (eq ! 'eof) !)))
   
   ;;;; User package.
   
  
positive.code: (defun filter (fun x) (mapcar fun x))
  (defun %set-elt (object sequence index) object sequence index (error "Not implemented."))
  
  (defun %fclose (stream-handle) stream-handle (error "Not implemented."))
  (defun %directory (pathname) pathname (error "Not implemented."))
  (defun %stat (pathname) pathname (error "Not implemented."))
  (defun readlink (pathname) pathname (error "Not implemented."))
  
negative.code:       builtin? macro?
        %%macroexpand %%macrocall %%%macro?
        %princ %force-output
        %fopen %fclose %read-char
        sys-image-create))
  
  (defun make-keyword (x)
  