📅  最后修改于: 2022-03-11 14:58:18.498000             🧑  作者: Mango
代码示例1
> (check-duplicates '(1 2 3 4))
#f
> (check-duplicates '(1 2 3 2 1))
2
> (check-duplicates '((a 1) (b 2) (a 3)) #:key car)
'(a 3)