public function start()
    {
        if ($this->active)
            return $this;

        if (PHP_SAPI === "cli")
        {
            $this->startCLISession();
        }
        else
        {
            // @codeCoverageIgnoreStart
            $this->startHTTPSession();
            // @codeCoverageIgnoreEnd
        }

        if (!$this->has('session_mgmt', 'start_time'))
            $this->set('session_mgmt', 'start_time', time());

        return $this;
    }