protected function contentToString()
    {
        $string = '';
        if (!is_null($this->content)) {
            foreach ($this->content as $c) {
                $string .= $c->toString();
            }
        }

        return $string;
    }
protected function contentToString()
    {
        $string = '';
        if (!is_null($this->content)) {
            foreach ($this->content as $c) {
                $string .= $c->toString();
            }
        }

        return $string;
    }
protected function contentToString ( ) { $ string = '' ; if ( ! is_null ( $ this -> content ) ) { foreach ( $ this -> content as $ c ) { $ string .= $ c -> toString ( ) ; } } return $ string ; }
return current list of content as a string
@return string
return current list of content as a string