Return the rank (or index) of member in the sorted set at key, with scores being ordered from
high to low.
<p>
When the given member does not exist in the sorted set, the special value 'nil' is returned.
The returned rank (or index) of the member is 0-based for both commands.
<p>
<b>Time complexity:</b>
<p>
O(log(N))
@see #zrank(string, string)
@param key
@param member
@return Integer reply or a nil bulk reply, specifically: the rank of the element as an integer
reply if the element exists. A nil bulk reply if there is no such element.
Return the rank (or index) of member in the sorted set at key, with scores being ordered from high to low. <p> When the given member does not exist in the sorted set, the special value 'nil' is returned. The returned rank (or index) of the member is 0-based for both commands. <p> <b>Time complexity:</b> <p> O(log(N)) @see #zrank(string, string) @param key @param member @return Integer reply or a nil bulk reply, specifically: the rank of the element as an integer reply if the element exists. A nil bulk reply if there is no such element.