example. Scheme 词法遮蔽的调用结果为 12[mce-lexical]
(run-scheme '((define x 10)
(define add-x (lambda (y) (+ x y)))
((lambda (x) (add-x 2)) 100)))⇒ 12 · checked
(run-scheme '((define x 10)
(define add-x (lambda (y) (+ x y)))
((lambda (x) (add-x 2)) 100)))⇒ 12 · checked