Method add_multi

code/chapter09/conshash.rs:51–57

批量插入结点

(&mut self, nodes: &[T])

    // 批量插入结点
    fn add_multi(&mut self, nodes: &[T]) {
        if !nodes.is_empty() {
            for node in nodes.iter() {
                self.add(node);
            }
        }
    }

    fn add(&mut self, node: &T) {
        for i in 0..self.replicas {