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: akv_mem.rs
    path of file: ./repos/code/ch7/ch7-actionkv/src
    
    the code of the file until where you have to start completion: use libactionkv::ActionKV;                // <1>

#[cfg(target_os 
    
fn main() {
  let args: Vec<String> = std::env::args().collect();
  let fname = args.get(1).expect(&USAGE);
  let action = args.get(2).expect(&USAGE).as_ref();
  let key = args.get(3).expect(&USAGE).as_ref();
  let maybe_value = args.get(4);

  let path = std::path::Path::new(&fname);
  let mut store = ActionKV::open(path).expect("unable to open file");
  store.load().expect("unable to load data");

  match action {
    "get" => match store.get(key).unwrap() {
      None => eprintln!("{:?} not found", key),
      Some(value) => println!("{:?}", value),
    },

    "delete" => store.delete(key).unwrap(),

    "insert" => {
      let value = maybe_value.expect(&USAGE).as_ref();
      store.insert(key, value).unwrap()
    }

    "update" => {
      let value = maybe_value.expect(&USAGE).as_ref();
      store.update(key, value).unwrap()
    }

    _ => eprintln!("{}", &USAGE),
  }
}