protected function flow($step)
    {
        // Carregar id do flow
        $flow = router()->current()->parameter('flow');
        if (is_null($flow)) {
            error('Flow not information');
        }

        // Carregar model
        $this->model = call_user_func_array([$this->modelName, 'find'], [$flow]);
        if (is_null($this->model)) {
            error('Flow "%s" not found', $flow);
        }

        // Carregar step
        $step = is_null($step) ? $this->model->steps->firstId() : $step;
        if (! $this->model->steps->exists($step)) {
            error('Step "%s" not found', $step);
        }

        $this->model->steps->setCurrent($step);

        return $this->model->steps->current();
    }