anchor.diff:    (error 'not-implemented :feature "${}"))
   
   (defun read-dollar-word (stream)
  -  (assert (equal #\$ (read-char stream nil :eof)))
     (let ((next-char (peek-char nil stream nil :eof)))
       (when (or (find next-char #(#\@ #\* #\# #\? #\- #\$ #\!))
                 (digit-char-p next-char))
  
positive.code: 
  (defun handle-dollar (stream initiation-sequence context)
    (declare (ignore initiation-sequence))
    (lexer-context-add-part context (read-dollar stream))
    t)
  
  (defun handle-backtick (stream initiation-sequence context)
  
negative.code:     (as-> *empty-shell-readtable* x
        (with-dispatch-character x "$")
        (with-default-handler x "$" 'handle-dollar)
        (with-handler x "${" 'handle-dollar-curly)
        (with-dispatch-character x "$(")
        (with-default-handler x "$(" 'handle-dollar-paren)
        (with-handler x "$((" 'handle-dollar-paren-paren)
        (with-handler x "`" 'handle-backtick)))
  
  (define-once-global +double-quote-readtable+
  