This command is equal to SINTER, but instead of returning the resulting set,
it is stored in destination.
If destination already exists, it is overwritten (when the intersection is nonempty) or deleted (when the intersection is empty).
@examples
SADD key1 "a"
SADD key1 "b"
SADD key1 "c"
SADD key2 "c"
SADD key2 "d"
SADD key2 "e"
SINTERSTORE key key1 key2
SMEMBERS key