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: key.rs
    path of file: ./repos/metrics/metrics/src
    
    the code of the file until where you have to start completion: use crate::{atomics::AtomicU64, cow::Cow, IntoLabels, KeyHasher, Label, SharedString};
use std::{
    borrow::Borrow,
    cmp, fmt,
    hash::{Hash, Hasher},
    slice::Iter,
    sync::atomic::{AtomicBool, Ordering},
};

const NO_LABELS: [Label; 0] = [];

/// Name component of a key.
#[derive(Clone, Debug, Eq, Hash, PartialEq, PartialOrd, Ord)]
pub struct KeyName(SharedString);

impl KeyName {
    /// Creates a `KeyName` fro
    
    fn test_key_name_equality() {
        static KEY_NAME: &'static str = "key_name";

        let borrowed_const = KeyName::from_const_str(KEY_NAME);
        let borrowed_nonconst = KeyName::from(KEY_NAME);
        let owned = KeyName::from(KEY_NAME.to_owned());

        let shared_arc = Arc::from(KEY_NAME);
        let shared = KeyName::from(Arc::clone(&shared_arc));

        assert_eq!(borrowed_const, borrowed_nonconst);
        assert_eq!(borrowed_const.as_str(), borrowed_nonconst.as_str());
        assert_eq!(borrowed_const, owned);
        assert_eq!(borrowed_const.as_str(), owned.as_str());
        assert_eq!(borrowed_const, shared);
        assert_eq!(borrowed_const.as_str(), shared.as_str());
    }