This command is similar to ZUNIONSTORE, but instead of storing the resulting
sorted set, it is returned to the client.
For a description of the WEIGHTS and AGGREGATE options, see ZUNIONSTORE.
Examples
127.0.0.1:6379> ZADD zset1 1 "one"
(integer) 1
127.0.0.1:6379> ZADD zset1 2 "two"
(integer) 1
127.0.0.1:6379> ZADD zset2 1 "one"
(integer) 1
127.0.0.1:6379> ZADD zset2 2 "two"
(integer) 1
127.0.0.1:6379> ZADD zset2 3 "three"
(integer) 1
127.0.0.1:6379> ZUNION 2 zset1 zset2
1) "one"
2) "three"
3) "two"
127.0.0.1:6379> ZUNION 2 zset1 zset2 WITHSCORES
1) "one"
2) "2"
3) "three"
4) "3"
5) "two"
6) "4"