anchor.diff:                  (let ,rebindings
                     ,@body))))))
   
  -;;;# `and-let*'
  +;;; `and-let*'
   
   (defmacro and-let* ((&rest clauses) &body body &environment env)
     "Scheme's guarded LET* (SRFI-2).
  
positive.code:   `(lret-aux let* ,bindings
       ,@body))
  
  ;;;# `letrec'
  
  ;;; Obviously `letrec' is less useful than in Scheme (where it is the
  ;;; way to construct recursive functions) but still sometimes useful;
  ;;; say, when initializing a timer whose function needs to refer to
  ;;; the timer itself.
  
  (defmacro letrec-with (setq (&rest bindings) &body body)
    `(let (,@(mapcar #'car bindings))
  
negative.code:           collect (list binding nil)
          else collect binding))
  
  ;;; `mvlet'
  
  ;; TODO Should mvlet* allow bindings to be repeated in a single
  ;; binding form? It would be more consistent with let*.
  