anchor.diff:    (print-cell c out)
     (format out ">"))
   
  +;;; ===================
  +;;; Character streams
  +;;; ===================
  +
   (defclass char-stream-cell (stream-cell)
     ((hd :initarg :hd)
      (tl :initform nil))
  
positive.code:     (char-seq in-stream :autoclose t)))
  
  (example
   (take 10 (file-char-seq (truename "./streams.lisp")))
   => '(#\Newline #\( #\i #\n #\- #\p #\a #\c #\k #\a))
  
  (defclass line-stream-cell (stream-cell)
    ((hd :initform nil)
     (tl :initform nil))
    (:documentation "A stream cell for character inputs."))
  
  (defclass byte-stream-cell (stream-cell)
    ((hd :initform nil)
  
negative.code:  closed when reaching the EOF. This may be dangerous (if the stream
   is shared) but is otherwise practical when working at the REPL.
  
  Also note that the stream is only closed when reaching the EOF.
  Use FLUSH-SEQ for forcing the close operation."
  
    (let ((ch (read-char in-stream nil :at-eof)))
  