SUNION key [key …]

    Time complexity: O(N) where N is the total number of elements in all given sets.

    Returns the members of the set resulting from the union of all the given sets.

    For example:

    Array reply: list with members of the resulting set.

    *Examples

    redis> SADD key1 "a"

      redis> SADD key1 "b" 

      1. (integer) 1

      redis> SADD key2 "c"

      redis> SADD key2 "d" 

      1. (integer) 1

      redis> SADD key2 "e" 

      1. 2) "c"
      2. 3) "d"
      3. 5) "e"
      redis>