code: public function orderByDesc(
          /*# string */ $col,
          /*# bool */ $rawMode = false,
          /*# sting */ $desc = 'DESC'
      ) {
          $this->clause_orderby[] = [
              $rawMode ?: $this->isRaw($col), $col, $desc
          ];
          return $this;
      }
docs: {@inheritDoc}