public function attr($key, $value = null)
    {
        if(is_array($key))
        {
            foreach($key as $k => $val)
                $this->attributes[$k] = $val;

            return $this;
        }
        elseif($value === null)
        {
            $this->attributeString[] = $key;

            return $this;
        }

        if($key == 'class')
            return $this->addClass($value);

        $this->attributes[$key] = $value;

        return $this;
    }