public function setInstance($instance = 'default')
    {
        $this->get($instance);

        $this->session->put($this->prefix.'.instance', $instance);

        if (!in_array($instance, $this->getInstances())) {
            $this->session->push($this->prefix.'.instances', $instance);
        }
        $this->events->dispatch('laracart.new');

        return $this;
    }