rmrevin\yii\fontawesome\component\Icon::li PHP Method

    public function li()
    {
        return $this->addCssClass(FA::$cssPrefix . '-li');
    }

 /**
  * @param string|Icon $icon
  * @param string|null $label
  * @param array $options
  * @return static
  */
 public function item($icon, $label = null, $options = [])
 {
     if (is_string($icon)) {
         $icon = new Icon($icon);
     }
     $content = trim((string) $icon->li() . $label);
     $this->items[] = Html::tag('li', $content, $options);
     return $this;
 }