1#[macro_export]
 2macro_rules! n_fold {
 3    ($tmp:ident, $v:ident, $func:ident, $count:ident) => {
 4        $tmp.$func(&$v[$count].1);
 5    };
 6
 7    ($tmp:ident, $func:ident) => {
 8        $tmp.$func();
 9    };
10}