ZSCORE key member
Available since: 1.2.0
Time complexity: O(1)
ACL categories:
@read
@sortedset
@fast
Returns the score of member in the sorted set at key.
If member does not exist in the sorted set, or key does not exist, nil is
returned.
Return
Bulk string reply: the score of member (a double precision floating point number),
represented as string.