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: read_dep_dir.rs
    path of file: ./repos/rules_rust/test/dep_env
    
    the code of the file until where you have to start completion: use std::{env::var, fs, io::Result};

fn main() {
    let dep_dir = &var("DEP_DIR").expect("DEP_DIR should be set");
    let entries = fs::read_dir(dep_dir)
        .expect("Failed to open DEP_DIR directory")
        .collect::<Result<Vec<_>>>()
        .expect("Failed to read DEP_DIR directory entries");
    let entries = entries
        .iter()
   
    
fn main() {
    let dep_dir = &var("DEP_DIR").expect("DEP_DIR should be set");
    let entries = fs::read_dir(dep_dir)
        .expect("Failed to open DEP_DIR directory")
        .collect::<Result<Vec<_>>>()
        .expect("Failed to read DEP_DIR directory entries");
    let entries = entries
        .iter()
        .map(|entry| {
            entry
                .path()
                .file_name()
                .unwrap()
                .to_string_lossy()
                .to_string()
        })
        .collect::<Vec<_>>();
    assert_eq!(entries, vec!["a_file".to_string()]);
}