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: magic_identifier.rs
    path of file: ./repos/turbo/crates/turbopack-ecmascript/src
    
    the code of the file until where you have to start completion: use std::{
    borrow::Cow,
    fmt::{Display, Write},
};

use once_cell::sync::Lazy;
use regex::{Captures, Regex, Replacer};

pub fn mangle(content: &str) -> String {
    let mut r = "__TURBOPACK__".to_string();
    let mut hex_mode = false;
    for c in content.chars() {
        if matches!(c, '0'..='9' | 'A'..='Z' | 'a'..='z' | ' ') {
            if hex_mode {
                r.push('$');
                hex_mode = false;
            }
            if c == ' ' {
                r += "__";
            } else {
                r.push(c);
            }
        } else if c == '_' && (!r.ends_with('_') || hex_mode) {
            if hex_mode {
                r.push('$');
                hex_mode = false;
            }
            r += "_";
        } else if c == '$' && !hex_mode {
            r += "$$";
        } else if matches!(c, '\0'..='\u{ff}') {
            if !hex_mode {
                r.push('$');
                hex_mode = true;
            }
            write!(r, "{0:2x}", c as u8).unwrap();
        } else {
            if !hex_mode {
                r.push('$');
            }
            write!(r, "_{:x}$", c as u32).unwrap();
            hex_mode = false;
        }
    }
    if hex_mode {
        r.push('$');
    }
    r += "__";
    r
}

/// Decodes a magic identifier into a string.
pub fn unmangle(identifier: &str) -> String {
    static DECODE_REGEX: Lazy<Regex> =
        Lazy::new(|| Regex::new(r"^__TURBOPACK__([a-zA-Z0-9_$]+)__$").unwrap());

    let Some(captures) = DECODE_REGEX.captures(identifier) else {
        return identifier.to_string();
    };

    let content = captures.get(1).unwrap().as_str();

    enum Mode {
        Text,
        Underscore,
        Hex,
        LongHex,
    }
    let mut mode = Mode::Text;
    let mut output = String::new();
    let mut buffer = String::with_capacity(2);
    for char in content.chars() {
        match mode {
            Mode::Text => match char {
                '_' => mode = Mode::Underscore,
                '$' => mode = Mode::Hex,
                c => output.push(c),
            },
            Mode::Underscore => match char {
                '_' => {
                    output.push(' ');
                    mode = Mode::Text;
                }
                '$' => {
                    output.push('_');
                    mode = Mode::Hex;
                }
                c => {
                    output.push('_');
                    ou
    
pub fn unmangle(identifier: &str) -> String {
    static DECODE_REGEX: Lazy<Regex> =
        Lazy::new(|| Regex::new(r"^__TURBOPACK__([a-zA-Z0-9_$]+)__$").unwrap());

    let Some(captures) = DECODE_REGEX.captures(identifier) else {
        return identifier.to_string();
    };

    let content = captures.get(1).unwrap().as_str();

    enum Mode {
        Text,
        Underscore,
        Hex,
        LongHex,
    }
    let mut mode = Mode::Text;
    let mut output = String::new();
    let mut buffer = String::with_capacity(2);
    for char in content.chars() {
        match mode {
            Mode::Text => match char {
                '_' => mode = Mode::Underscore,
                '$' => mode = Mode::Hex,
                c => output.push(c),
            },
            Mode::Underscore => match char {
                '_' => {
                    output.push(' ');
                    mode = Mode::Text;
                }
                '$' => {
                    output.push('_');
                    mode = Mode::Hex;
                }
                c => {
                    output.push('_');
                    output.push(c);
                    mode = Mode::Text;
                }
            },
            Mode::Hex => {
                if buffer.len() == 2 {
                    if let Ok(byte) = u8::from_str_radix(&buffer, 16) {
                        output.push(byte as char);
                    }
                    buffer.clear();
                }
                match char {
                    '_' => {
                        debug_assert!(buffer.is_empty());
                        mode = Mode::LongHex;
                    }
                    '$' => {
                        debug_assert!(buffer.is_empty());
                        mode = Mode::Text;
                    }
                    c => {
                        buffer.push(c);
                    }
                }
            }
            Mode::LongHex => {
                debug_assert!(char != '_');
                match char {
                    '$' => {
                        if let Ok(code) = u32::from_str_radix(&buffer, 16) {
                            output.push(std::char::from_u32(code).unwrap());
                        }
                        buffer.clear();
                        mode = Mode::Text;
                    }
                    c => {
                        buffer.push(c);
                    }
                }
            }
        }
    }
    debug_assert!(matches!(mode, Mode::Text));
    output
}