public function addTag($key, $value)
    {
        $key = trim($key);
        if ($key === '') {
            throw new Exception('Tag Key must not be empty', 1448264366);
        }
        $value = trim($value);
        if ($value === '') {
            throw new Exception('Tag Value must not be empty', 1448264367);
        }
        $tag = Functions::ucfirst($key) . 'DynamicTag_' . $value;
        $this->tags[$tag] = true;
    }