SDIFFSTORE

    1. dragonfly> SADD key1 "a"
    2. (integer) 1
    3. dragonfly> SADD key1 "b"
    5. (integer) 1
    6. dragonfly> SADD key2 "c"
    7. (integer) 1
    8. dragonfly> SADD key2 "d"
    10. dragonfly> SADD key2 "e"
    11. (integer) 1
    12. (integer) 2
    13. dragonfly> SMEMBERS key
    15. 2) "a"