# Pastebin 0trAUJbz
Welcome to Racket v8.15.0.2 [cs].
> (require syntax/free-vars)
> (define v (expand #'(define (twice prc) (lambda (x) (prc (prc x))))))
> (define s (syntax-case v () [(_ _ e) #'e]))
> s
#<syntax:string:1:20 (lambda (prc) (lambda (x) (#%app prc (#%app prc x))))>
> (free-vars s)
'()