SISMEMBER
Syntax
        SISMEMBER key member
- Available since:
- 1.0.0
- Time complexity:
- O(1)
- ACL categories:
- 
              
                @read,@set,@fast,
Returns if member is a member of the set stored at key.
Return
Integer reply, specifically:
- 1if the element is a member of the set.
- 0if the element is not a member of the set, or if- keydoes not exist.