anchor.diff:  
   (defvar *call/cc-returns* nil)
   
  -(defmacro with-call/cc (initial-environment &body body)
  +(defmacro with-call/cc (&environment e &body body)
     "Execute BODY with delimited partial continuations.
   
     Within the code of BODY almest all common lisp forms maintain
  
positive.code:   passed a continutaion. This object may then be passed to the
    function KALL which will cause execution to resume around the
    call/cc form. "
    (let ((walk-env nil)
          (evaluate-env nil))
      (assert (every (lambda (binding)
                       (and (consp binding)
                            (= 2 (length binding))))
                     initial-environment)
              (initial-environment)
              "Sorry, INITIAL-ENVIRONMENT must be a list of two element lists, not: ~S"
              initial-environment)
      (loop
         for (name value) in initial-environment
         do (setf walk-env (register walk-env :let name value)
                  evaluate-env `(register ,evaluate-env :let ',name ,value)))
      `(drive-cps (evaluate/cps ,(walk-form (if (rest body)
                                                `(progn ,@body)
                                                (first body))
  
negative.code: ;;;; Variable References
  
  (defmethod evaluate/cps ((var local-variable-reference) env k)
    (kontinue k (lookup env :let (name var) :error-p t)))
  
  (defmethod evaluate/cps ((var local-lexical-variable-reference) env k)
    (kontinue k (funcall (first (lookup env :lexical-let (name var) :error-p t)))))
  
  (defmethod evaluate/cps ((var free-variable-reference) env k)
    (declare (ignore env))
  