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: clif-json.rs
    path of file: ./repos/wasmtime/cranelift/serde/src
    
    the code of the file until where you have to start completion: //! Utility for `cranelift_serde`.

#![deny(missing_docs)]

use clap::Parser;
use cranelift_codegen::ir::Function;
use cranelift_reader::parse_functions;
use std::fs::File;
use std::io;
use std::io::prelude::*;
use std::process;

fn call_ser(file: &str, pretty: bool) -> Result<(), String> {
    let ret_of_parse = parse_functions(file);
    match ret_of_parse {
        Ok(funcs) => {
            let ser_str = if pretty {
                serde_json::to_string_pretty(&funcs).unwrap()
            } else {
                serd
    
fn main() {
    let res_serde = match Args::parse() {
        Args::Serialize { pretty, file } => {
            let mut contents = String::new();
            let mut file = File::open(file).expect("Unable to open the file");
            file.read_to_string(&mut contents)
                .expect("Unable to read the file");

            call_ser(&contents, pretty)
        }
        Args::Deserialize { file } => {
            let file = File::open(file).expect("Unable to open the file");
            call_de(&file)
        }
    };

    if let Err(mut msg) = res_serde {
        if !msg.ends_with('\n') {
            msg.push('\n');
        }
        io::stdout().flush().expect("flushing stdout");
        io::stderr().write_all(msg.as_bytes()).unwrap();
        process::exit(1);
    }
}