public function setDefaultClass($class, $element = 'li'){
        if(in_array($element, ['a', 'li', 'ul']) && ((is_string($class) && !empty(trim($class))) || is_bool($class))) {
            $this->menuElements[strtolower($element).'_default'] = $class;
        }
        elseif(in_array($element, $this->allowedElements)){
            $this->menuElements[strtolower($element)] = $class;
        }
        return $this;
    }