anchor.diff:          (and therefore usable by #+clisp SOCKET:SOCKET-STATUS).
   "
     (etypecase stream
  +
  +    (echo-stream
  +     (ecase direction
  +       (:output (bare-stream (echo-stream-output-stream stream)
  +                             :direction direction))
  +       (:input  (bare-stream (echo-stream-input-stream  stream)
  +                             :direction direction))))
       (two-way-stream
        (ecase direction
          (:output (bare-stream (two-way-stream-output-stream stream)
                                :direction direction))
          (:input  (bare-stream (two-way-stream-input-stream stream)
  -                             :direction direction))))
  -    (echo-stream
  -     (ecase direction
  -       (:output (bare-stream (echo-stream-output-stream stream)
  -                             :direction direction))
  -       (:input  (bare-stream (echo-stream-input-stream  stream)
                                :direction direction))))
       (synonym-stream
        (bare-stream (symbol-value (synonym-stream-symbol stream))
  
positive.code: ;; RETURN: An output-stream.
  ;; "
  ;;   (etypecase stream
  ;;     (two-way-stream  (two-way-stream-output-stream stream))
  ;;     (echo-stream     (echo-stream-output-stream  stream))
  ;;     (synonym-stream  (stream-output-stream
  ;;                       (symbol-value (synonym-stream-symbol stream))))
  ;;     (t
  
negative.code: ;; RETURN: An input-stream.
  ;; "
  ;;   (etypecase stream
  ;;     (echo-stream         (echo-stream-input-stream  stream))
  ;;     (two-way-stream      (two-way-stream-input-stream stream))
  ;;     (synonym-stream      (stream-input-stream
  ;;                           (symbol-value (synonym-stream-symbol stream))))
  ;;     (concatenated-stream (stream-input-stream
  