Method remove

code/chapter09/conshash.rs:75–81

(&mut self, node: &T)

    }

    fn remove(&mut self, node: &T) {
        assert!(!self.ring.is_empty());
        for i in 0..self.replicas {
            let key = hash(&format!("{}{}", node.to_string(), i.to_string()));
            self.ring.remove(&key);
        }
    }

    // 查询结点
    fn get(&self, key: u64) -> Option<&T> {