src/HtmlElementAbstract.php
public function addContent($content = null)
    {
        if (!is_null($content)) {
            $htmlElementObject = new HtmlElementContent($content);
            $this->getChildElementCollection()->add($htmlElementObject);
        }
        return $this;
    }
public function addContent($content = null)
    {
        if (!is_null($content)) {
            $htmlElementObject = new HtmlElementContent($content);
            $this->getChildElementCollection()->add($htmlElementObject);
        }
        return $this;
    }
add html element content

@param       string      $content        html element content
@return      HtmlElementAbstract