anchor.diff:  The `local' macro is loosely based on Racket's support for internal
   definitions."
     (multiple-value-bind (body decls) (parse-body orig-body)
  -    (let (vars hoisted-vars labels *in-let* *orig-form* exprs *symbol-macros*)
  +    (let (vars hoisted-vars labels *in-let* *orig-form* exprs symbol-macros)
         (labels ((in-subenv? ()
                    "Are we within a binding form?"
  -                 (or *in-let* *symbol-macros*))
  +                 (or *in-let* symbol-macros))
                  (at-beginning? ()
                    "Return non-nil if this is the first form in the `local'."
                    (not (or vars hoisted-vars labels (in-subenv?))))
  
positive.code: 
  (defvar *in-let*)
  (defvar *orig-form*)
  (defvar *symbol-macros*)
  
  (defmacro nonlocal (&body body)
    `(progn ,@body))
  
negative.code:                  "Shorthand for recursing on an implicit `progn'."
                   `(progn ,@(mapcar #'expand-partially body)))
                 (symbol-macro (name exp)
                   (push (list name exp) symbol-macros))
                 (shadow-symbol-macro (name)
                   ;; Note that this removed /all/ instances.
                   (removef symbol-macros name :key #'car))
                 (expansion-done (form)
                   (setf form (wrap-symbol-macros form))
                   (push form exprs)
  