anchor.diff:        (arity-error vm primitive-arity num-args))
       (multiple-value-bind(result what-next)
           (if is-required-primitive
  -            (apply primitive (reverse arg-values))
  +            (apply primitive arg-values)
               (handler-case
  -                (apply primitive (reverse arg-values))
  +                (apply primitive arg-values)
                 (error (err)
                   (setf (vm-user-defined-primitive-error vm) err)
                   (values :null :nap-and-retry-on-wake-up))))
  
positive.code:               (incf (vm-program-counter vm))
                (apply-return-address vm (pop (vm-stack vm))))
            (push result (vm-stack vm)))))))
  
  (defun set-in-environment (environment frame-number var-index value)
    (setf (second (aref (env-frame-vars (nth frame-number environment))
  
negative.code:   (with-output-to-string (str)
      (write-environment (vm-current-environment vm) vm str)))
  
  (declaim (inline vm-is-live))
  (defun vm-is-live (vm)
    (declare (optimize speed)
             (inline vm-execution-complete))
  