anchor.diff:        (any (lambda (p) (contains x p)) form)))
   
   (define (β-reduce form)
  -  (cond ((or (atom form) (constantp form)) form)
  -
  +  (if (or (atom form) (constantp form))
  +      form
  +    (β-reduce- (map β-reduce form))))
  +
  +(define (β-reduce- form)
           ; ((lambda (f) (f arg)) X) => (X arg)
  -        ((and (= (length form) 2)
  +  (cond ((and (= (length form) 2)
                 (consp (car form))
                 (eq (caar form) 'lambda)
                 (let ((args (cadr (car form)))
  
positive.code: 
  - handle dotted arglists in lambda
  
   here's an alternate way to transform a while loop:
  
   (let ((x 0))
  
negative.code:                               ,s
                                ,@params)))))))
  
          (T form)))
  
  (defmacro with-delimited-continuations code (cps (f-body code)))
  
  