Html::link problem

I use the bellow code and I have the error


Call to undefined method yii\helpers\Html::link()

what is wrong?I want to "print" a link at a gridview column.


use yii\helpers\Html;

$a=Html::link('Files',Html::a( 'files', $url ));

There is no link() method in the Html helper class.

http://www.yiiframework.com/doc-2.0/yii-helpers-html.html

Wouldn’t it be sufficient to use only this:


$a = Html::a('Files', $url);