You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: mod.rs
    path of file: ./repos/clash-nyanpasu/backend/tauri/src/config/clash
    
    the code of the file until where you have to start completion: use crate::utils::{
    dirs,
    help::{self, get_clash_external_port},
};
use anyhow::Result;
use log::warn;
use serde::{Deserialize, Serialize};
use serde_yaml::{Mapping, Value};
use std::{
    net::{IpAddr, Ipv4Addr, SocketAddr},
    str::FromStr,
};
use tracing_attributes::instrument;

use super::Config;

#[derive(Default, Debug, Clone)]
pub struct IClashTemp(pub Mapping);

impl IClashTemp {
    pub fn new() -> Self {
        match dirs::clash_path().and_then(|path| help::read_merge_mapping(&path)) {
            Ok(map) => Self(Self::guard(map)),
            Err(err) => {
     
    
    pub fn guard_server_ctrl(config: &Mapping) -> String {
        config
            .get("external-controller")
            .and_then(|value| match value.as_str() {
                Some(val_str) => {
                    let val_str = val_str.trim();

                    let val = match val_str.starts_with(':') {
                        true => format!("127.0.0.1{val_str}"),
                        false => val_str.to_owned(),
                    };

                    SocketAddr::from_str(val.as_str())
                        .ok()
                        .map(|s| s.to_string())
                }
                None => None,
            })
            .unwrap_or("127.0.0.1:9090".into())
    }