0. #lang racket
1. (require racket/generator)
2. (define id (generator (op)
3.               (let loop ([p op])
4.                 (let loop ([a (car p)]
5.                            [b (cdr p)])
6.                         (loop (yield a b)))))
7.                   )
8.  
9. (display (id (cons 2 3)))
10. (display (id (cons 3 4)))

=>

result arity mismatch;

expected number of values not received

expected: 1

received: 2

values...:

2

3

loop: arity mismatch;

the expected number of arguments does not match the given

number

expected: 2

given: 1

arguments...:

'(3 . 4)