ZCOUNT
Syntax
        ZCOUNT key min max
- Available since:
 - 2.0.0
 - Time complexity:
 - O(log(N)) with N being the number of elements in the sorted set.
 - ACL categories:
 - 
              
                
@read,@sortedset,@fast, 
Returns the number of elements in the sorted set at key with a score between
min and max.
The min and max arguments have the same semantic as described for
ZRANGEBYSCORE.
Note: the command has a complexity of just O(log(N)) because it uses elements ranks (see ZRANK) to get an idea of the range. Because of this there is no need to do a work proportional to the size of the range.