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: build.rs
    path of file: ./repos/coreutils/wc
    
    the code of the file until where you have to start completion: use std::{env, fs::File, io::BufWriter};

use clap::crate_name;
use clap_generate::{Generator, Shell};

#[path = "src/cli.rs"]
mod cli;

fn main() {
    let mut app = cli::create_app();
    app.set_bin_name(crate_name!());

    let out_dir = match env::var("OUT_DIR") {
        Ok(dir) => dir,
        Err(err) => {
            eprintln!("No OUT_DIR: {}", err);
            return;
        },
    };


    let shells = [Shell::Bash, Shell::Elvish, Shell::Fish, Shell::PowerShell, Shell::Zsh];

    for shell in shells {
        let file_name = format!("{}/{}", out_dir, shell.file_name(app.get_name()));
        let mut file = BufWriter::new(
           
    
fn main() {
    let mut app = cli::create_app();
    app.set_bin_name(crate_name!());

    let out_dir = match env::var("OUT_DIR") {
        Ok(dir) => dir,
        Err(err) => {
            eprintln!("No OUT_DIR: {}", err);
            return;
        },
    };


    let shells = [Shell::Bash, Shell::Elvish, Shell::Fish, Shell::PowerShell, Shell::Zsh];

    for shell in shells {
        let file_name = format!("{}/{}", out_dir, shell.file_name(app.get_name()));
        let mut file = BufWriter::new(
            File::options()
                .read(true)
                .write(true)
                .create(true)
                .open(file_name)
                .expect("Unable to open file"),
        );

        shell.generate(&app, &mut file)
    }
}