docs: def rank_for_in(self, leaderboard_name, member):
          '''
          Retrieve the rank for a member in the named leaderboard.
  
          @param leaderboard_name [String] Name of the leaderboard.
          @param member [String] Member name.
          @return the rank for a member in the leaderboard.
          '''
          member_score = self.score_for_in(leaderboard_name, member)
          if self.order == self.ASC:
              try:
                  return self.redis_connection.zrank(
                      self._ties_leaderboard_key(leaderboard_name), str(float(member_score))) + 1
              except:
                  return None
          else:
              try:
                  return self.redis_connection.zrevrank(
                      self._ties_leaderboard_key(leaderboard_name), str(float(member_score))) + 1
              except:
                  return None