ZPOPMIN key [count]
Time complexity: O(log(N)*M) with N being the number of elements in the sorted set, and M being the number of elements popped.
Removes and returns up to members with the lowest scores in the sorted set stored at .
Array reply: list of popped elements and scores.
*Examples
redis> ZADD myzset 1 "one"
redis> ZADD myzset 3 "three"
redis> ZPOPMIN myzset