code: public function status($status = NULL) {
          if ($status === NULL) {
              return $this->status;
          } elseif (array_key_exists($status, Response::$messages)) {
              $this->status = (int)$status;
              $this->status_message = Response::$messages[$this->status];
              return $this;
          } else {
              throw new Exception(__METHOD__ . ' unknown status value : :value', array(':value' => $status));
          }
      }
docs: Sets or gets the HTTP status from this response.
  
  @param   integer $status Status to set to this response
  @return  mixed