anchor.diff:  (defmethod object-rope ((object rope-node))
     object)
   
  +(defmethod object-rope ((object character))
  +  object)
  +
  +(defmethod object-rope ((object symbol))
  +  object)
  +
   (defun rope-map (function sequence
                    &key
                      (start 0)
  
positive.code:     (rope-node (rope-node-length rope))
      (simple-string (length rope))
      (string (length rope))
      (symbol (length (symbol-name rope)))))
  
  (defun %rope-cat (first second)
    (make-rope-node :length (+ (rope-length first)
  
negative.code: ;;;   - use heap-based stack for very deep ropes
  
  (deftype rope ()
    `(or string symbol rope-node character null))
  
  (defconstant +rope-newline+
    '|
  