(PS: 1. First, set up your own SearXNG search engine server: https://docs.searxng.org/
 2. For servers like SearXNG that do not require an apiKey, you don't need to concern yourself with auth_name and api_key.
 3. For servers that require passing an apiKey, auth_name would be the key in the header, and api_key would be the value. Note that custom parameters are not yet supported for input.)

For SearXNG-like search engine servers that do not require authentication:
  You need to set the server address in one of two ways:
    Method One: Environment variable: export SEARXNG_URL="http://192.168.26.xxx:18080/search"
    Method Two: Assign the URL when initializing SearxngSearch: tool = SearxngSearch(url="")
    If both methods are used, the value from method one takes precedence.
For search engine servers that require authentication:
  Omitted
Args:
    api_key (str): API key, default is 'sk-xxxx'.
    auth_name (str): Authentication name, default is 'searxng'.
    language (str): Language setting, default is 'zh'.
    categories (str): Category setting, default is 'general'.
    url (str): URL of the SearXNG service, default is 'http://127.0.0.1:18883'.
    topk (int): Number of top results to return, default is 3.
    black_list (List[str]): Blacklist of domains you do not wish to see in search results.
    **kwargs: Other variable keyword arguments, such as proxy settings.

 SearXNG之类不需要鉴权的搜索引擎服务端：
  需要设置服务端地址：两种方式：
    方式一：环境变量：export SEARXNG_URL="http://192.168.26.xxx:18080/search"
    方式二：初始化SearxngSearch时赋值url； tool = SearxngSearch(url="")
    若两者都设置，以方式一的值为准
  需要鉴权的搜索引擎服务端：
    略
Args:
    api_key (str): API密钥，默认值为'sk-xxxx'。
    auth_name (str): 认证名称，默认值为'searxng'。
    language (str): 语言设置，默认值为'zh'。
    categories (str): 类别设置，默认值为'general'。
    url (str): SearXNG服务的URL，默认值为'http://127.0.0.1:18883'。
    topk (int): 返回的顶部结果数量，默认值为3。
    black_list (List[str]): 黑名单列表，包含不希望搜索到的域名。
    **kwargs: 其他可变关键字参数，如代理设置。