del books_zset
zadd books_zset 9.0 "think in java"
zadd books_zset 8.9 "java concurrency"
zadd books_zset 8.6 "java cookbook"
zrange books_zset 0 -1
zrevrange books_zset 0 -1
zcard books_zset
zscore books_zset "java concurrency"
zrank books_zset "java concurrency"
zrangebyscore books_zset -inf 8.91 withscores
zrem books_zset "java concurrency"
zrange books_zset 0 -1