NonexistentCommands
                
                    A list of commands that don't exist in Redis, but can be accomplished in a different way.
                
                
                    
This is a list of commands that don't exist in Redis, but can be accomplished in a different way, usually by means of 
WATCH/MULTI/EXEC.
For better performance, you can pipeline multiple commands.
GETSET for Hashes.
WATCH foo
old_value = HGET foo field
MULTI
HSET foo field new_value
EXEC
See 
SETEX.
Add an element to a sorted set, only if the element doesn't already exist (by default, 
ZADD would update the element's score if it already exists). 
See thread.
WATCH foo
score = ZSCORE foo bar
IF score != NIL
  MULTI
  ZADD foo 1 bar
  EXEC
ENDIF