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: exclusivity_guard.rs
    path of file: ./repos/ros2_rust/rclrs/src/wait
    
    the code of the file until where you have to start completion: use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::Arc;

use crate::RclrsError;

/// A helper struct for tracking whether the waitable is currently in a wait set.
///
/// When this struct is constructed, which happens when add
    
    fn test_exclusivity_guard() {
        let atomic = Arc::new(AtomicBool::new(false));
        let eg = ExclusivityGuard::new((), Arc::clone(&atomic)).unwrap();
        assert!(ExclusivityGuard::new((), Arc::clone(&atomic)).is_err());
        drop(eg);
        assert!(!atomic.load(Ordering::Relaxed));
        assert!(ExclusivityGuard::new((), Arc::clone(&atomic)).is_ok());
    }