WATCH
Syntax
        WATCH key [key ...]
- Available since:
 - 2.2.0
 - Time complexity:
 - O(1) for every key.
 - ACL categories:
 - 
              
                
@fast,@transaction, 
Marks the given keys to be watched for conditional execution of a transaction.
RESP2/RESP3 Reply
Simple string reply:OK.