PhpCss\Ast\Visitor\Css::visitEnterSelectorGroup PHP Method

    public function visitEnterSelectorGroup(Ast\Selector\Group $group)
    {
        if (!empty($this->_buffer)) {
            throw new \LogicException(sprintf('Visitor buffer already contains data, can not visit "%s"', get_class($group)));
        }
        return TRUE;
    }