src/HtmlListAbstract.php
public function addItem($content, $value = null)
    {
        $this->addChildElement(new HtmlListItem($content, $value));
        return $this;
    }
public function addItem($content, $value = null)
    {
        $this->addChildElement(new HtmlListItem($content, $value));
        return $this;
    }
add select option

@param       string      $content    list item content
@param       string      $value      list item attribute value
@return      HtmlListAbstract